Abstract:
A communication device may include a processor, a memory storing computer-readable instructions, and a Near Field Communication (NFC) interface. The computer-readable instructions may instruct of otherwise cause the communication device to perform determining whether a state of the communication device is a first state. In a case where the state of the communication device is determined to be the first state, the NFC interface may establish a first type of communication link and transmit first data to the first external device via the first type of communication link. Additionally or alternatively, in a case where the state of the communication device is determined not to be the first state, the NFC interface may establish a second type of communication link, the second type of communication link and communicate second data with the second external device via the second type of communication link.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 14/228,425 filed Mar. 28, 2014 which claims priority from Japanese Patent Application No. 2013-068623, filed on Mar. 28, 2013, the content of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Aspects disclosed herein relate to a technique used in a communication device. 
     BACKGROUND 
     An electrical device is equipped with a short-range wireless communication device. The short-range wireless communication device automatically switches its mode between an Initiator mode and a Responder mode at a predetermined timing. The short-range wireless communication device changes a ratio between a period of operation in the Initiator mode and a period of operation in the Responder mode in accordance with a status of a power supply connected to the electrical device. 
     SUMMARY 
     There may be required a new technique for enabling an electrical device to operate appropriately in accordance with a status of the electrical device itself. 
     Accordingly, some embodiments provide for a new communication device that may operate appropriately in accordance with a status of the communication device itself. 
     According to one or more aspects of the disclosure, a communication device may include a processor, a memory storing computer-readable instructions, and a Near Field Communication (NFC) interface. The computer-readable instructions, when executed by the processor, may instruct of otherwise cause the communication device to perform determining whether a state of the communication device is a first state. The NFC interface may perform communication using an NFC system compliant with an NFC standard. Additionally or alternatively, the NFC interface may perform several various. In one example, in a case where the state of the communication device is determined to be the first state, the NFC interface may establish a first type of communication link between the communication device and a first external device and transmit first data to the first external device via the first type of communication link after the first type of communication link is established. Additionally or alternatively, in a case where the state of the communication device is determined not to be the first state, the NFC interface may establish a second type of communication link between the communication device and a second external device, the second type of communication link being different from the first type of communication link and communicate second data, different from the first data, with the second external device via the second type of communication link after the second type of communication link is established. 
     According to the above-described configuration, the communication device may be configured to determine whether the communication device is in the first state where the communication device needs to transmit the first data. Accordingly, the communication device may be configured to operate in an appropriate operation mode in accordance with whether the communication device is in the first state. Thus, the communication device may be configured to perform appropriate communication with one of the first and second external devices in accordance with the operation mode of the communication device. Additionally, the communication device may be configured to operate appropriately in accordance with the state of the communication device. 
     Control methods and computer programs for implementing the above-described communication device, computer programs, and computer-readable storage media storing the computer programs may also have novelty and utility. Communication systems including the above-described communication device and at least one of a plurality of external devices may also have novelty and utility. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following descriptions taken in connection with the accompanying drawings. 
         FIG. 1  illustrates a configuration of a communication system in an illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 2  is a flowchart depicting an example communication process performed by a multifunction peripheral (“MFP”) in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 3  is a flowchart depicting an example CE mode process performed by the MFP in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 4  is a flowchart depicting an example Writer mode process performed by the MFP in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 5  is a flowchart depicting an example Reader mode process performed by the MFP in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 6  is a flowchart depicting an example P2P mode process performed by the MFP in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 7  is a sequence diagram depicting communication performed between devices when the MFP operates in a CE mode in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 8  is a sequence diagram depicting communication performed between devices when the MFP operates in a Writer mode in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 9  is a sequence diagram depicting communication performed between devices when the MFP operates in a Reader mode in the illustrative embodiment according to one or more aspects of the disclosure. 
         FIG. 10  is a sequence diagram depicting communication performed between devices when the MFP operates in a P2P mode in the illustrative embodiment according to one or more aspects of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an illustrative embodiment will be described with reference to the accompanying drawings. Referring to  FIG. 1 , an example configuration of a communication system  2  will be described. The communication system  2  includes an access point (“AP”)  6 , a personal computer (“PC”)  8 , a multifunction peripheral (“MFP”)  10 , mobile terminals  50  and  80 , and an identification card  100 . Each of the MFP  10 , the mobile terminals  50  and  80 , and the identification card  100  is configured to perform communication using a communication system that complies with a Near Field Communication (“NFC”) standard (i.e., an NFC system). Short-range wireless communication may include wireless communication in compliance with the NFC system. In this illustrative embodiment, wireless communication using the NFC system is performed in compliance with the International standard, e.g., ISO/IEC 21481 or ISO/IEC 18092. 
     Each of the PC  8 , the MFP  10 , and the mobile terminals  50  and  80  is configured to perform wireless communication using a system in compliance with a Wi-Fi Direct (hereinafter, referred to as a “WFD system”). In the WFD system, wireless communication is performed in compliance with the standard IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 802.11 and its family standards (e.g., 802.11a, 802.11b, 802.11g, and 802.11n). A communication method (i.e., the standards for wireless communication) differs between the NFC system and the WFD system. For example, the communication method of the WFD system has a higher communication speed than the communication method of the communication speed of the NFC system. 
     For example, a WFD network may be configured by establishment of a connection (hereinafter, referred to as a “WFD connection”) between the MFP  10  and the mobile terminal  50  using the WFD system. Likewise, another WFD network may be configured by establishment of a WFD connection between the MFP  10  and the PC  8 . 
     The PC  8 , the MFP  10 , and the mobile terminals  50  and  80  are further configured to perform wireless communication using a basic Wi-Fi system that differs from wireless communication using the WFD system. In one example, wireless communication using the basic Wi-Fi system may be wireless communication using the AP  6 , and wireless communication using the WFD system may be wireless communication without using the AP  6 . For example, the MFP  10  is allowed to belong to a basic Wi-Fi network by establishment of a connection between the MFP  10  and the AP  6  (hereinafter, referred to as a “basic Wi-Fi connection”) in accordance with the basic Wi-Fi system. The MFP  10  is allowed to perform wireless communication with another device (e.g., the PC  8  or the mobile terminal  50 ) that belongs in the basic Wi-Fi network, via the AP  6 . A communication method (i.e., the standards for wireless communication) differs between the NFC system and the basic Wi-Fi system. For example, the communication method of the basic Wi-Fi system may have a higher communication speed than the communication method of the communication speed of the NFC system. 
     Referring to  FIG. 1 , a configuration of the MFP  10  will be described. The MFP  10  includes an operation unit  12 , a display unit  14 , a printing execution unit  16 , a scanning execution unit  18 , a wireless LAN interface (“I/F”)  20 , an NFC interface (“I/F”)  22 , and a control device  24 . The operation unit  12  includes a plurality of keys. The user is allowed to input various instructions into the MFP  10  by operating the operation unit  12 . The display unit  14  includes a display that is configured to display various information thereon. The printing execution unit  16  includes a printing mechanism using one of an inkjet method and a laser method. The scanning execution unit  18  includes a scanning mechanism using one of a charge-coupled device (“CCD”) and a contact image sensor (“CIS”). 
     The wireless LAN I/F  20  is configured to allow the control device  24  to perform one of wireless communication using the WFD system and wireless communication using the basic Wi-Fi system. The wireless LAN I/F  20  includes a single interface physically. Nevertheless, the wireless LAN I/F  20  is assigned with a media access control (“MAC”) address used in wireless communication using the WFD system (hereinafter, referred to as a “MAC address for WFD system”) and a MAC address used in wireless communication using the basic Wi-Fi system (hereinafter, “MAC address for basic Wi-Fi system”). More specifically, the MAC address for basic Wi-Fi system is assigned to the wireless LAN I/F  20  in advance. The control device  24  generates the MAC address for WFD system, using the MAC address for basic Wi-Fi system, and assigns the generated MAC address for WFD system to the wireless LAN I/F  20 . In some arrangements, the MAC address for WFD system differs from the MAC address for basic Wi-Fi system. Therefore, the control device  24  is capable of performing both wireless communication using the WFD system and wireless communication using the basic Wi-Fi system simultaneously via the wireless LAN I/F  20 . Consequently, there occurs a situation in which the MFP  10  belongs in both the WFD network and the basic Wi-Fi network at the same time. In other embodiments, for example, physically independent chips may be used as the interface configured to perform wireless communication using the WFD system and the interface configured to perform wireless communication using the basic Wi-Fi system. 
     The user is allowed to change a setting of the wireless LAN I/F  20  by operating the operation unit  12 . The setting of the wireless LAN I/F  20  is switched between a setting that wireless communication using the WFD system is available (hereinafter, this setting is referred to as “the WFD I/F setting indicates “ON””) and a setting that wireless communication using the WFD system is unavailable (hereinafter, this setting is referred to as “the WFD I/F setting indicates “OFF””). A central processing unit (“CPU”)  30  stores a value indicating a detail (e.g., “ON” or “OFF”) of the WFD I/F setting designated by the user in a memory  32 . 
     The NFC I/F  22  is configured to allow the control device  24  to perform wireless communication using the NFC system. The wireless LAN I/F  20  and the NFC I/F  22  are implemented by physically independent chips. 
     A communication speed (e.g., a maximum communication speed is 11 to 600 Mbps) of wireless communication via the wireless LAN I/F  20  may be faster than a communication speed (e.g., a maximum communication speed is 106 to 424 kbps) of wireless communication using the NFC I/F  22 . A frequency (e.g., 2.4 GHz band or 5.0 GHz band) of a carrier in wireless communication using the wireless LAN I/F  20  may also differ from a frequency (e.g., 13.56 MHz band) of a carrier in wireless communication using the NFC I/F  22 . The CPU  30  is allowed to perform wireless communication using the NFC system between the MFP  10  and one of the mobile terminals  50  and  80  via the NFC I/F  22  in a situation where a distance between the MFP  10  and the one of the mobile terminals  50  and  80  is shorter than approximately 10 cm. The CPU  30  is allowed to perform wireless communication using one of the WFD system and the basic Wi-Fi system, between the MFP  10  and one of the mobile terminals  50  and  80  via the wireless LAN I/F  20 , in a situation where the distance between the MFP  10  and the one of the mobile terminals  50  and  80  is longer than, shorter than or equal to approximately 10 cm (e.g., a maximum communicable distance is approximately 100 m). That is, a maximum distance that the MFP  10  can communicate with a communication target device (e.g., the mobile terminal  50 ) wirelessly via the wireless LAN I/F  20  is longer than a maximum distance that the MFP  10  can communicate with the communication target device wirelessly via the NFC I/F  22 . 
     The control device  24  includes the CPU  30  and the memory  32 . The CPU  30  performs various processes in accordance with a program (e.g., instructions) stored in the memory  32 . The memory  32  includes a read-only memory (“ROM”), a random-access memory (“RAM”), and a hard disk. The memory  32  stores the above-described program to be executed by the CPU  30 . 
     According to some configurations, the program may include an application program and a protocol stack. The application program is designed to enable the CPU  30  to perform a process at an application layer in an Open System Interconnection (“OSI”) reference model. The protocol stack is designed to enable the CPU  30  to perform a process at a lower layer underlying the application layer in the OSI reference model. The protocol stack includes a Peer-to-Peer (“P2P”) program, an R/W program, and a CE program. The P2P program is a program for performing a process in accordance with a P2P mode of the NFC standard. The R/W program is a program for performing a process in accordance with a Reader/Writer mode of the NFC standard. The CE program is a program for performing a process in accordance with a Card Emulation (“CE”) mode of the NFC standard. These programs are programs for performing processes that comply with the NFC standard specified by the NFC Forum. 
     When the MFP  10  belongs to the WFD network, the CPU  30  stores, in the memory  32 , information indicating that the MFP  10  belongs to the WFD network and a wireless setting (e.g., an authentication method, an encryption method, a password, a service set identifier (“SSID”) of the wireless network, and a basic service set identifier (“BSSID”)) for performing communication of target data (e.g., print data or scan data) via the WFD network. When the MFP  10  belongs to the basic Wi-Fi network, the CPU  30  stores, in the memory  32 , information indicating that the MFP  10  belongs to the basic Wi-Fi network and a wireless setting for performing communication of target data via the basic Wi-Fi network. The SSID is an identifier for identifying a wireless network. The BSSID is a unique identifier (e.g., a MAC address) of an access point that configures a wireless network (e.g., a device having a group owner (“G/O”) status in the WFD network). 
     The memory  32  stores the value indicating the detail (e.g., “ON” or “OFF”) of the WFD I/F setting therein. In some examples, the control device  24  is not allowed to perform various processes in accordance with the WFD system in a state where the WFD I/F setting stored in the memory  32  indicates “OFF”. In a state where the WFD I/F setting indicates “ON”, the memory  32  further stores a WFD-system-related value indicating a current status (e.g., a G/O status, a client status, or a device status) of the MFP  10 . 
     The memory  32  further stores an URL (hereinafter, referred to as an “application download URL”) for allowing another device (e.g., the mobile terminal  50 ) to download an application program (hereinafter, referred to as an “application for MFP”) that enables the other device to perform various functions (e.g., one or more of the printing function and the scanning function) using the MFP  10 . The memory  32  further stores an URL of a webpage that describes how to resolve a device error (e.g., a paper jam or a breakdown of a printing mechanism occurring in the printing execution unit  16 ) that may occur in the MFP  10  (hereinafter, referred to as a “support page URL”). The device error will be described in further detail below. The memory  32  further stores a URL of a webpage for introducing consumable items (e.g., ink (toner), and sheets) that may be used in the MFP  10  (hereinafter, referred to as a “consumable item URL”). The application download URL, the support page URL, and the consumable item URL may be pre-stored in the memory  32  by a vendor of the MFP  10 . 
     The memory  32  further stores a value indicating a detail (e.g., “ON” or “OFF”) of an application URL provision mode setting. The “application URL provision mode” enables the MFP  10  to provide another terminal with the above-described application download URL. The user is allowed to switch the setting of the application URL provision mode between “ON” and “OFF” by operating the operation unit  12 . The CPU  30  stores, in the memory  32 , the value indicating the detail (e.g., “ON” or “OFF”) of the application URL provision mode setting designated by the user. 
     The memory  32  is further configured to store a writing job therein. When the CPU  30  receives a writing job from the PC  8  via the AP  6 , the CPU  30  stores the writing job in the memory  32 . The writing job includes writing data designated by the user (e.g., a URL designated by the user and/or text inputted by the user). The memory  32  is further configured to store a print job therein. When the CPU  30  receives a print job from the PC  8  via the AP  6 , the CPU  30  stores the print job in the memory  32 . The print job includes print data desired to be printed, e.g., by the user. In the illustrative embodiment, authentication using the identification card  100  is required in order for the MFP  10  to perform printing based on the print data. 
     Next, communication using the NFC system will be further described. Hereinafter, a device that is capable of performing communication using the NFC system (e.g., the MFP  10 , the mobile terminals  50  and  80 , and the identification card  100 ) is referred to as an “NFC-enabled device”. Hereinafter, a Reader mode and a Writer mode are referred to as an “R/W mode”. 
     Among NFC-enabled devices, there is a device in which all the three modes of the P2P mode, the R/W mode, and the CE mode are available and another device in which one or two of the three modes are available. In the illustrative embodiment, all of the above-described three modes are available in each of the MFP  10  and the mobile terminals  50  and  80 . The identification card  100  is designed to comply with the NFC standard (also referred to as an “NFC-compliant card”). More specifically, the CE mode is available but the P2P mode and the R/W mode are not available in the identification card  100 . 
     The P2P mode provides two-way communication between NFC-enabled devices in a pair. It is assumed that the P2P mode is active in both of a first NFC-enabled device and a second NFC-enabled device. In this case, a communication link appropriate for the P2P mode (hereinafter, referred to as a “P2P communication link”) is established between the first NFC-enabled device and the second NFC-enabled device. Under this situation, for example, the first NFC-enabled device transmits first predetermined data to the second NFC-enabled device via the P2P communication link. Then, the second NFC-enabled device transmits second predetermined data to the first NFC-enabled device via the same P2P communication link. Thus, two-way communication is implemented. An NFC-enabled device that is compliant with ISO/IEC 1443 Type A defined by the NFC Forum and an NFC-enabled device that is compliant with ISO/IEC 18092 Type F defined by the NFC Forum are both capable of using the P2P mode. Nevertheless, an NFC-enabled device that is compliant with ISO/IEC 1443 Type B defined by the NFC Forum is not capable of using the P2P mode. 
     The R/W mode and the CE mode both provide one-way communication between NFC-enabled devices in a pair. The CE mode enables an NFC-enabled device to operate as a “card” in a form defined by the NFC Forum. The NFC-enabled device of Type A, the NFC-enabled device of Type F, and the NFC-enabled device of Type B are capable of using the CE mode. The Reader mode enables an NFC-enabled device to read data from another NFC-enabled device that operates in the CE mode as a card. The Writer mode enables an NFC-enabled device to write data in another NFC-enabled device that operates in the CE mode as a card. The Reader mode also enables an NFC-enabled device to read data from an NFC-compliant card (e.g., the identification card  100 ). The Writer mode also enables an NFC-enabled device to write data in the NFC-compliant card. 
     For example, in one scenario, the Reader mode is active in the first NFC-enabled device and the CE mode is active in the second NFC-enabled device. In this case, a communication link appropriate for the Reader mode and the CE mode is established between the first NFC-enabled device and the second NFC-enabled device. Under this situation, the first NFC-enabled device performs an operation for reading data from a pseudo card in the second NFC-enabled device via the communication link to receive the data from the second NFC-enabled device. 
     In another example, if the Writer mode is active in the first NFC-enabled device and the CE mode is active in the second NFC-enabled device, a communication link appropriate for the Writer mode and the CE mode is established between the first NFC-enabled device and the second NFC-enabled device. Under this situation, the first NFC-enabled device performs an operation for writing data into the pseudo card in the second NFC-enabled device via the communication link to transmit the data to the second NFC-enabled device. 
     As described above, various combinations of the modes are available to perform communication using the NFC system between NFC-enabled devices in a pair. For example, for the combinations of the modes in the pair of NFC-enabled devices, the following five patterns are available: a “P2P mode and P2P mode” pair, a “Reader mode and CE mode” pair, a “Writer mode and CE mode” pair, a “CE mode and Reader mode” pair, and a “CE mode and Writer mode” pair. 
     An NFC-enabled device cannot create a situation in which both the Reader mode and the Writer mode are active simultaneously. That is, while the Reader mode is active, the Writer mode is inactive in the NFC-enabled device. While the Writer mode is active, the Reader mode is in inactive in the NFC-enabled device. 
     The NFC-enabled devices are configured to establish therebetween a communication link appropriate for an active mode but not configured to establish therebetween a communication link appropriate for an inactive mode. For example, when the CE mode is active and the P2P mode and the R/W mode are inactive in the MFP  10 , the MFP  10  is allowed to establish a communication link for enabling the MFP  10  to operate in the CE mode. Nevertheless, the MFP  10  is not allowed to establish another communication link (e.g., a communication link for enabling the MFP  10  to operate in the inactive P2P mode, the inactive Reader mode, or the inactive Writer mode). 
     Next, the WFD will be described. The WFD is a standard created by the Wi-Fi Alliance and is specified in the “Wi-Fi Peer-to-Peer (P2P) Technical Specification Version 1.1” drafted by the Wi-Fi Alliance. 
     As described above, the PC  8 , the MFP  10 , and the mobile terminals  50  and  80  are configured to perform thereamong wireless communication using the WFD system. Hereinafter, a device that is capable of performing wireless communication in compliance with the WFD system is referred to as a “WFD-enabled device”. The WFD standard defines three statuses of the WFD-enabled device: a G/O status, a client status, and a device status. The WFD-enabled device is configured to operate selectively in one of the three statuses. 
     A wireless network is configured by a device having the G/O status (hereinafter, also referred to as a “G/O-status device”) and one or more devices having the client status (hereinafter, also referred to as a “client-status device”). In a wireless network, one or more client-status devices are present while only one G/O-status device is present. The G/O-status device is configured to control the one or more client-status devices. More specifically, the G/O-status device is configured to generate a management list that describes identifying information (e.g., a media access control (“MAC”) address) of the one or more client-status devices. When a new client-status device participates in the wireless network, the G/O-status device adds identifying information of the new client-status device on the management list. When one of the one or more client-status devices leaves the wireless network, the G/O-status device erases the identifying information of the departing or departed client-status device. 
     The G/O-status device is configured to perform wireless communication of target data (e.g., data including information on a network layer of the OSI reference model (e.g., print data or scan data)) with one of the one or more devices that are listed in the management list, such as one of the one or more client-status devices (e.g., one or more devices belonging to the WFD network). The G/O-status device is configured to not perform wireless communication of the target data with a client-status device that is not listed in the management list. The G/O-status device, however, is configured to perform wireless communication of data for participating in the wireless network (e.g., data not including the information on the network layer such as a Probe Request packet or data of a physical layer of a Probe Response packet) with the unlisted client-status device. For example, the MFP  10  having G/O status is allowed to receive print data via wireless communication from the mobile terminal  50  (e.g., the mobile terminal  50  having client status) listed in the management list but is not allowed to receive print data via wireless communication from a device not listed in the management list. 
     The G/O-status device is configured to serve as a relay station configured to relay wireless communication between a plurality of the client-status devices that transmit target data (e.g., print data or scan data) therebetween. For example, when the mobile terminal  50  having the client status transmits print data via wireless communication to another printer having the client status, the mobile terminal  50  transmits the print data via wireless communication to the MFP  10  having the G/O status first and the MFP  10  then transmits the print data via wireless communication to the printer having the client status. That is, the G/O-status device is configured to function as the AP in the basic WFD network. 
     The WFD-enabled device that is absent from the wireless network (e.g., a WFD-enabled device not listed in the management list) is a device having the device status (hereinafter, also referred to as a “device-status device”). The device-status device is configured to perform wireless communication of the data for participating in the WFD network (e.g., a Probe Request packet or data of a physical layer of a Probe Response packet) with the G/O-status device but is not allowed to perform wireless communication of target data (e.g., print data or scan data) with the G/O-status device via the WFD network. 
     Next, configurations of the mobile terminals  50  and  80  will be further described with reference to  FIG. 1 . The mobile terminal  50  may include a mobile phone (e.g., smartphone), a personal digital assistant (“PDA”), a notebook PC, a tablet PC, a mobile music player, and/or a mobile video player. The mobile terminal  80  may have the same configuration as the mobile terminal  50 . The mobile terminal  50  includes an operation unit  52 , a display unit  54 , a wireless LAN interface (“I/F”)  56 , an NFC interface (“I/F”)  58 , and a control device  60 . The operation unit  52  includes a plurality of keys. The display unit  54  includes a display configured to display various information thereon. In other embodiments, for example, the mobile terminal  50  may include a touch panel having functions of both the operation unit  52  and the display unit  54 . 
     The wireless LAN I/F  56  and the NFC I/F  58  have the same configuration as the wireless LAN I/F  20  and the NFC I/F  22 , respectively, of the MFP  10 . That is, the control device  60  is allowed to perform wireless communication using the WFD system and wireless communication using the basic Wi-Fi system via the wireless LAN I/F  56  simultaneously. The control device  60  is also allowed to perform wireless communication using the NFC system via the NFC I/F  58 . 
     The control device  60  includes a CPU  62  and a memory  64 . The CPU  62  is configured to perform various processes in accordance with a program stored in the memory  64 . The memory  64  includes a ROM, a RAM, and a hard disk. The memory  64  stores the above program that is executed by the CPU  62 . The program includes an application program and a protocol stack, similar to the program stored in the memory  32  of the MFP  10 . The application program includes an application program that is designed to enable the MFP  10  to perform various functions (e.g., a printing function and/or a scanning function) (hereinafter, referred to as an “application for MFP”). As described below with reference to  FIG. 7 , upon receipt of an application download URL from the MFP  10 , the CPU  62  accesses an Internet server (not depicted) offered by the vendor of the MFP  10 , using the application download URL. Then, the CPU  62  downloads and installs the application for MFP in the memory  64  from the server. 
     The memory  64  stores a first operation system (“OS”) program. The first OS program enables the mobile terminal  50  to operate as described below. For example, as power of the mobile terminal  50  is turned on, the mobile terminal  50  enters in an initial status in which the Reader mode is active and the other modes are inactive. In a case where the application for MFP has not yet been installed on the mobile terminal  50 , the mobile terminal  50  maintains the initial status. In a case where the application for MFP was installed on the mobile terminal  50  but has not been started yet, the mobile terminal  50  also maintains the initial status. As the application for MFP starts, the mobile terminal  50  changes from the initial status to a status in which the P2P mode is active and the other modes (e.g., the R/W mode and the CE mode) are inactive. 
     A configuration of the identification card  100  will be described below. The identification card  100  is provided to the user of the PC  8 . As described above, the identification card  100  is an NFC-compliant card, and the CE mode is available while the P2P mode and the R/W mode are not available in the identification card  100 . In the communication system  2  according to the illustrative embodiment, when the MFP  10  belongs to a wireless network including the AP  6  and the PC  8 , the MFP  10  receives a print job from the PC  8  via the AP  6  in some cases. The print job includes print data. Even when the MFP  10  receives the print job from the PC  6 , the MFP  10  does not start printing until authentication using the identification card  100  succeeds. The identification card  100  stores authentication data (e.g., a user ID and a password) used for authentication performed in the MFP  10 . Referring to  FIG. 9 , the user of the PC  8  brings the identification card  100  closer to the MFP  10  after the user transmits a print job from the PC  8  to the MFP  10 . The MFP  10  receives the authentication data (e.g., the user ID and the password) from the identification card  100  to perform an authentication process. In response to successful authentication, the MFP  10  starts printing. Thus, the user of the PC  8  may obtain a printed matter while the user is present near the MFP  10 . Printing in this manner may reduce a risk that a third party takes the printed matter away from the MFP  10 . 
     Next, a Polling operation and a Listen operation performed by an NFC-enabled device are described. For example, in the MFP  10 , the NFC I/F  22  performs the Polling operation and the Listen operation in accordance with the program. In the Polling operation, the NFC I/F  22  transmits a polling signal and receives a response signal transmitted in response to the polling signal. In the Listen operation, the NFC I/F  22  receives a polling signal and transmits a response signal in response to the polling signal. 
     The NFC I/F  22  of the MFP  10  is configured to operate selectively in one of a Polling mode of performing the Polling operation, a Listen mode of performing the Listen operation, and a mode of performing none of the Polling operation and the Listen operation (hereinafter, referred to as a “nonperformance mode”). The NFC I/F  22  operates in one of the Polling mode, the Listen mode, and the nonperformance mode selectively in turn. For example, the NFC I/F  22  may perform a one-cycle operation in which the NFC I/F  22  operates in the Polling mode first, and then operates in the Listen mode, and finally operates in the nonperformance mode. The NFC I/F  22  may perform the one-cycle operation repeatedly. 
     In the Polling mode, the NFC I/F  22  transmits a polling signal and then monitors receipt of a response signal. More specifically, the NFC I/F  22  (1) transmits a polling signal to which an NFC-enabled device of Type A can respond (e.g., a polling signal for Type A) and monitors receipt of a response signal for a predetermined time period, (2) if a response signal has not been received, transmits a polling signal to which an NFC-enabled device of Type B can respond (e.g., a polling signal for Type B) and monitors receipt of a response signal for a predetermined time period, (3) if a response signal has not been received, transmits a polling signal to which an NFC-enabled device of Type F can respond (e.g., a polling signal for Type F) and monitors receipt of a response signal for a predetermined time period. The NFC I/F  22  repeats the above operation. When the NFC I/F  22  receives a response signal from an NFC-enabled device (i.e., a communication target) within the predetermined time period in one of the steps in the above operation, the communication target is determined as an NFC-enabled device of Type that corresponds to the polling signal that the NFC-enabled device receives immediately before transmitting the response signal. When the NFC I/F  22  receives a response signal from a communication target, the NFC I/F  22  further transmits, to the communication target, an inquiry signal to inquire which of the modes is active in the NFC-enabled device that transmitted the response signal. 
     In the Listen mode, the NFC I/F  22  monitors receipt of a polling signal. Upon receipt of a polling signal, the NFC I/F  22  transmits a response signal. The NFC I/F  22  transmits a response signal to an NFC-enabled device (e.g., a communication target) that is a sender of the polling signal only when the NFC I/F  22  receives the polling signal for the type corresponding to the NFC I/F  22 . When the NFC I/F  22  transmits the response signal to the communication target, the NFC I/F  22  further receives the inquiry signal from the communication target. Thus, the NFC I/F  22  transmits an active mode signal to the communication target. 
     In the nonperformance mode, the NFC I/F  22  does not transmit either a polling signal or a response signal even when the NFC I/F  22  receives a polling signal. 
     The mobile terminals  50  and  80  also repeatedly perform the one-cycle operation independently. Therefore, for example, when a period during which the NFC I/F  22  of the MFP  10  operates in the Polling mode overlaps a period during which the mobile terminal  50  operates in the Listen mode while the distance between the MFP  10  and the mobile terminal  50  is shorter than 10 cm, the NFC I/F  22  performs the Polling operation of transmitting a polling signal to the mobile terminal  50  and receiving a response signal from the mobile terminal  50 . For example, when a period during which the NFC I/F  22  of the MFP  10  operates in the Listen mode overlaps a period during which the mobile terminal  50  operates in the Polling mode while the distance between the MFP  10  and the mobile terminal  50  is shorter than 10 cm, the NFC I/F  22  performs the Listen operation of receiving a polling signal from the mobile terminal  50  and transmitting a response signal to the mobile terminal  50 . Hereinafter, an NFC-enabled device that performs the Polling operation is referred to as a “Polling device” and an NFC-enabled device that performs the Listen operation is referred to as a “Listen device”. 
     When the NFC I/F  22  performs the Polling operation, that is, when the MFP  10  is a Polling device, subsequent processes to be performed for communication are carried on by the CPU  30 . More specifically, first, the NFC I/F  22  passes, to the CPU  30 , the information indicating which one of the modes that a communication target serving as a Listen device (e.g., the mobile terminal  50 ) can operate in (e.g., the information indicated by the received active mode signal). 
     For example, in a case where the MFP  10  serving as a Polling device is currently in a state where the P2P mode is active and the CE mode and the R/W mode are inactive and the information passed from the NFC I/F  22  indicates that the communication target serving as a Listen device is currently in a state where the P2P mode is active, the CPU  30  transmits an Activation command corresponding to the P2P mode to the communication target and then receives an OK command from the communication target. Thus, a P2P communication link is established between the MFP  10  serving as a Polling device and the communication target serving as a Listen device. 
     In another example, in a case where the MFP  10  serving as a Listen device is currently in a state where the P2P mode is active and the CE mode is inactive and the communication target serving as a Polling device is currently in a state where the P2P mode is active, the CPU  30  receives an Activation command corresponding to the P2P mode from the communication target. In this case, the CPU  30  determines that the MFP  10  needs to operate in the P2P mode, and transmits an OK command to the communication target. Thus, a P2P communication link is established between the MFP  10  serving as a Listen device and the communication target serving as a Polling device. 
     In still another example, in a case where the MFP  10  serving as a Listen device is currently in a state where the CE mode is active and the P2P mode is inactive and the communication target serving as a Polling device is currently in a state where one of the Reader mode and the Writer mode is active, the CPU  32  receives an Activation command corresponding to the R/W mode from the communication target. In this case, the CPU  32  determines that the MFP  10  needs to operate in the CE mode, and transmits an OK command to the communication target. Thus, a communication link appropriate for the CE mode and the R/W mode is established between the MFP  10  serving as a Listen device and the communication target serving as a Polling device. 
     In a case where the communication link appropriate for the CE mode and the R/W mode is established, the CPU  32  further receives, from the communication target, information indicating which one of the Reader mode and the Writer mode that the communication target operates in. Therefore, for example, when the CPU  32  receives information indicating that the communication target operates in the Reader mode, a communication link appropriate for the CE mode and the Reader mode (hereinafter, referred to as an “MFP(CE)-target(R) communication link”) is established between the MFP  10  serving as a Listen device and the communication target serving as a Polling device. For another example, when the CPU  32  receives information that the communication target operates in the Writer mode, a communication link appropriate for the CE mode and the Writer mode (hereinafter, referred to as an “MFP(CE)-target(W) communication link”) is established between the MFP  10  serving as a Listen device and the communication target serving as a Polling device. 
     In yet another example, in a case where the MFP  10  serving as a Polling device is currently in a state where the Writer mode is active and the other modes are inactive and the information passed from the NFC I/F  22  indicates that the communication target serving as the Listen device is currently in a state where the P2P mode is active, a communication link is not be established between the MFP  10  serving as a Polling device and the communication target serving as a Listen device. Nevertheless, in this case, the CPU  30  detects that the P2P mode is active in the communication target (e.g., YES in step S 76  in  FIG. 4 ). 
     Likewise, in a case where the MFP  10  serving as a Polling device is currently in a state where the Reader mode is active and the other modes are inactive and the information passed from the NFC I/F  22  indicates that the communication target serving as a Listen device is currently in a state where the P2P mode is active, a communication link is not established between the MFP  10  serving as a Polling device and the communication target serving as a Listen device. Nevertheless, in this case, also, the CPU  30  detects that the P2P mode is active in the communication target (e.g., YES in step S 98  in  FIG. 5 ). 
     The PC  8  includes a wireless LAN I/F (e.g., an interface for WFD system and basic Wi-Fi system) but does not include an NFC I/F. Therefore, the PC  8  is allowed to perform communication with the MFP  10  via the wireless LAN but is not allowed to perform wireless communication using the NFC system. The PC  8  includes a driver program that enables the MFP  10  to perform one or more functions (e.g., a printing function and/or a scanning function). Normally, the driver program is installed on the PC  8  using a medium shipped with the MFP  10 . Nevertheless, in other embodiments, for example, the driver program may be installed on the PC  8  from a server offered by the vendor of the MFP  10 . 
     The AP  6  is not a G/O-status device in the WFD system. The AP  6  is a common AP, e.g., called a wireless access point or a wireless LAN router. The AP  6  is configured to establish a basic Wi-Fi connection with a plurality of devices. Thus, a basic Wi-Fi network including the AP  6  and the plurality of devices is configured. The AP  6  receives data from one of the plurality of devices belonging to the basic Wi-Fi network, and transmits the data to another of the plurality of devices. Accordingly, the AP  6  is configured to relay communication between a pair of devices belonging to the basic Wi-Fi network. 
     Referring to  FIG. 2 , a detail of a communication process performed by the CPU  30  of the MFP  10  in accordance with the program will be further described. As the power of the MFP  10  is turned ON, the CPU  30  starts the communication process depicted in  FIG. 2 . After the communication process starts, the CPU  30  performs a determination in one or more of steps S 10 , S 12 , S 14 , S 16 , and S 18  sequentially. 
     In step S 10 , the CPU  30  determines whether a device error has occurred in the MFP  10 . The device error includes errors caused by any reasons except a consumable item being empty. For example, the device error may include a paper jam occurring in the printing execution unit  16  or a breakdown in the printing mechanism. The device error may further include a breakdown in the scanning execution unit  18  or a breakdown in the sensor. In step S 10 , the CPU  30  checks conditions of the units or portions of the MFP  10  (e.g., the printing execution unit  16  and the scanning execution unit  18 ). As a result of the condition check, when the CPU  30  determines that the device error has occurred, the CPU  30  makes a positive determination (e.g., YES) in step S 10 , and the routine proceeds to step S 24 . In step S 24 , the CPU  30  starts the CE mode. Thus, the MFP  10  starts operating in the CE mode. In step S 24 , the CPU  30  does not start the other modes (e.g., the P2P mode and the R/W mode). In step S 26 , the CPU  30  stores, in the NFC I/F  22 , a URL of a webpage describing how to resolve the device error occurring in the MFP  10  (e.g., the support page URL). More specifically, the CPU  30  stores the support page URL stored in the memory  32  into the chip constituting the NFC I/F  22 . Subsequent to step S 26 , the routine proceeds to step S 36  and the CPU  30  performs a CE mode process (see  FIG. 3 ). When the CPU  30  determines that a device error has not occurred in the MFP  10 , the CPU  30  makes a negative determination (e.g., NO) in step S 10 , and the routine proceeds to step S 12 . 
     In step S 12 , the CPU  30  determines whether a consumable item error has occurred in the MFP  10 . The consumable item error includes the absence or close to absence of a consumable item such as toner (or ink) or a sheet in the printing execution unit  16 . The CPU  30  checks a condition of each consumable item in the printing execution unit  16 . When the CPU  30  determines that the condition of at least one of the consumable items is insufficient to perform printing, the CPU  30  makes a positive determination (e.g., YES) in step S 12 , and the routine proceeds to step S 28 . In step S 28 , the CPU  30  starts the CE mode. Thus, the MFP  10  starts operating in the CE mode. In step S 28 , the CPU  30  does not start the other modes (e.g., the P2P mode and the R/W mode). In step S 30 , the CPU  30  stores, in the NFC I/F  22 , a URL of a webpage for introducing consumable items (e.g., ink (or toner) and/or sheets) to be used in the MFP  10  (e.g., the consumable item URL). In one example, the CPU  30  stores the consumable item URL stored in the memory  32  into the chip constituting the NFC I/F  22 . Subsequent to step S 30 , the routine proceeds to step S 36  and the CPU  30  performs the CE mode process (see  FIG. 3 ). When the CPU  30  determines that the conditions of all of the consumable items are sufficient to perform printing, the CPU  30  makes a negative determination (e.g., NO) in step S 12 , and the routine proceeds to step S 14 . 
     In step S 14 , the CPU  30  determines whether the application URL provision mode is enabled in the MFP  10 . For example, in step S 14 , the CPU  30  determines whether the value indicating the detail of the application URL provision mode setting stored in the memory  32  indicates “ON”. When the value representing the application URL provision mode setting indicates “ON”, the CPU  30  makes a positive determination (e.g., YES) in step S 14 , and the routine proceeds to step S 32 . In step S 32 , the CPU  30  starts the CE mode. Thus, the MFP  10  starts operating in the CE mode. In step S 32 , the CPU  30  does not start the other modes (e.g., the P2P mode and the R/W mode). In step S 34 , the CPU  30  stores an application download URL in the NFC I/F  22 . More specifically, the CPU  30  stores the application download URL stored in the memory  32  into the chip constituting the NFC I/F  22 . Subsequent to step S 34 , the routine proceeds to step S 36  and the CPU  30  performs the CE mode process (see  FIG. 3 ). When the value indicating the application URL provision mode setting stored in the memory  32  indicates “OFF”, the CPU  30  makes a negative determination (e.g., NO) in step S 14 , and the routine proceeds to step S 16 . 
     In step S 16 , the CPU  30  determines whether there is a writing job. For example, in step S 16 , the CPU  30  determines whether the memory  32  stores a writing job therein. As described above, when the CPU  30  receives a writing job from the PC  8  via the AP  6 , the CPU  30  stores the received writing job in the memory  32 . When the memory  32  stores a writing job therein, the CPU  30  makes a positive determination (e.g., YES) in step S 16 , and the routine proceeds to step S 38 . In step S 38 , the CPU  30  starts the Writer mode. Thus, the MFP  10  starts operating in the Writer mode. In step S 38 , the CPU  30  does not start the other modes. Then, in step S 40 , the CPU  30  performs a Writer mode process (see  FIG. 4 ). When the memory  32  does not store a writing job therein, the CPU  30  makes a negative determination (e.g., NO) in step S 16 , and the routine proceeds to step S 18 . According to this configuration, the MFP  10  may operate in the Writer mode appropriately when the CPU  30  determines that the MFP  10  is in a state where the MFP  10  does not need to transmit the URL (e.g., the support page URL, the consumable item URL, or the application download URL) to the outside (e.g., an external destination) and has a writing job stored therein (e.g., YES in step S 16 ). 
     In step S 18 , the CPU  30  monitors the presence of a print job that requires authentication. For example, in step S 18 , the CPU  30  determines whether the memory  32  stores a print job therein. As described above, when the CPU  30  receives a print job from the PC  8  via the AP  6 , the CPU  30  stores the received print job in the memory  32 . As described above, the MFP  10  does not perform printing unless authentication is performed using the identification card  100 . When the memory  32  stores a print job therein, the CPU  30  makes a positive determination (e.g., YES) in step S 18 , and the routine proceeds to step S 42 . In step S 42 , the CPU  30  starts the Reader mode. Thus, the MFP  10  starts operating in the Reader mode. In step S 42 , the CPU  30  does not start the other modes. In step S 44 , the CPU  30  performs a Reader mode process (see  FIG. 5 ). When the memory  32  does not store a print job, the CPU  30  makes a negative determination (e.g., NO) in step S 18 , and the routine proceeds to step S 20 . According to this configuration, the MFP  10  may operate in the Reader mode appropriately when the CPU  30  determines that the MFP  10  is in a state where the MFP  10  does not need to transmit the URL (e.g., the support page URL, the consumable item URL, or the application download URL) to the outside and does not have a writing job but a print job stored therein (e.g., YES in step S 18 ). 
     In step S 20 , the CPU  30  starts the P2P mode. Thus, the MFP  10  starts operating in the P2P mode. In step S 20 , the CPU  30  does not start the other modes. Then, in step S 22 , the CPU  30  performs a P2P mode process (see  FIG. 6 ). 
     As described above, in the illustrative embodiment, when a negative determination (e.g., NO) is made in each of steps S 10 , S 12 , S 14 , S 16 , and S 18  in  FIG. 2 , the CPU  30  places the operation mode of the MFP  10  in the P2P mode (e.g., step S 20 ). When the MFP  10  operates in the P2P mode, the MFP  10  is not in any state in which the MFP  10  needs to transmit the URL (e.g., the support page URL, the consumable item URL, and the application download URL), the state where the MFP  10  has a writing job therein, and the state where the MFP  10  has a print job therein. Therefore, according to the configuration of the illustrative embodiment, the MFP  10  may operate in an appropriate operation mode in accordance with the state of the MFP  10 . 
     Referring to  FIG. 3 , a detail of the CE mode process (e.g., step S 36  in  FIG. 2 ) performed by the CPU  30  of the MFP  10  will be described. The CE mode process is performed by the CPU  30  of the MFP  10  operating in the CE mode. As the CE mode process starts, the CPU  30  performs monitoring in one or more of steps S 50  and S 54 . 
     In step S 50 , the CPU  30  monitors establishment of an MFP(CE)-target(R) communication link. As described above, when the CPU  30  receives an Activation command corresponding to the Reader mode from the communication target (e.g., the mobile terminal  50 ), the CPU  30  determines that the MFP(CE)-target(R) communication link has been established. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 50 , and ends the CE mode process (e.g.  FIG. 3  and step S 36  in  FIG. 2 ). 
     When the CPU  30  determines that the MFP(CE)-target(R) communication link has been established (e.g., YES in step S 50 ), the NFC I/F  22  transmits the stored URL (e.g., the support page URL, the consumable item URL, or the application download URL) to the communication target automatically using the established MFP(CE)-target(R) communication link. According to this configuration, the MFP  10  may transmit an appropriate URL (e.g., the support page URL, the consumable item URL, or the application download URL) to the communication target using the MFP(CE)-target(R) communication link. 
     In step S 54 , the CPU  30  monitors establishment of an MFP(CE)-target(W) communication link. As described above, when the CPU  30  receives an Activation command corresponding to the Writer mode from the communication target (e.g., the mobile terminal  50 ) operating in the Writer mode, the CPU  30  determines that the MFP(CE)-target(W) communication link has been established. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 54 , and the routine proceeds to step S 56 . 
     In step S 56 , the CPU  30  monitors receipt of an execution request from the communication target via the NFC I/F  22  using the MFP(CE)-target(W) communication link. The execution request is a request signal for requesting an execution of a particular function (e.g., the scanning function or the printing function) of the MFP  10 . When the CPU  30  receives an execution request from a communication target operating in the Writer mode, the CPU  30  makes a positive determination (e.g., YES) in step S 56 , and the routine proceeds to step S 58 . When the CPU  30  does not receive an execution request from the communication target within a predetermined timeout period or when the CPU  30  receives information other than the execution request from the communication target, the CPU  30  makes a negative determination (e.g., NO) in step S 56 , and the routine proceeds to step S 64 . 
     In step S 58 , the CPU  30  determines whether the MFP  10  is capable of performing the particular function indicated by the execution request. For example, when the particular function is printing, in step S 58 , the CPU  30  checks the condition of the printing execution unit  16  to determine whether one or both of a device error (e.g., a paper jam or a breakdown of the printing mechanism) and a consumable item error (e.g., toner (ink) empty or sheet empty) have occurred. As the result of the condition check, when the CPU  30  determines that none of the device error and the consumable item error has occurred in the printing execution unit  16 , the CPU  30  determines that the particular function is executable. Even if a device error has occurred in the scanning execution unit  18 , the CPU  30  determines that the particular function is executable (e.g., printing is executable) when the particular function is printing. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 58 , and the routine proceeds to step S 60 . In a case where at least one of a device error and a consumable item error has occurred in the printing execution unit  16  when the particular function is printing, the CPU  30  determines that the particular function is non-executable. In this case, the CPU  30  makes a negative determination (e.g., NO) in step S 58 , and the routine proceeds to step S 64 . 
     Likewise, for example, when the particular function is scanning, in step S 58 , the CPU  30  checks the condition of the scanning execution unit  18  to determine whether a device error (e.g., a breakdown of the document conveyor mechanism or a breakdown of the sensor) has occurred. As a result of the condition check, when the CPU  30  determines that a device error has not occurred in the scanning execution unit  18 , the CPU  30  determines the particular function is executable. Although one or both of a device error and a consumable item error have occurred in the printing execution unit  16 , the CPU  30  determines that the particular function is executable (e.g., scanning is executable) when the particular function is scanning. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 58 , and the routine proceeds in step S 60 . In a case where a device error has occurred in the scanning execution unit  18  when the particular function is scanning, the CPU  30  determines that the particular function is non-executable. In this case, the CPU  30  makes a negative determination (e.g., NO) in step S 58 , and the routine proceeds to step S 64 . 
     In step S 64 , the CPU  30  displays, on the display unit  14 , an error screen including a message indicating that the particular function is non-executable. Subsequent to step S 64 , the CPU  30  ends the CE mode process (e.g.,  FIG. 3  and step S 36  in  FIG. 2 ). 
     In step S 60 , the CPU  30  ends the CE mode and starts the P2P mode. For example, first, the CPU  30  disconnects the MFP(CE)-target(W) communication link. That is, the CPU  30  performs communication (reception and transmission) of a Deactivation command and an OK command. The NFC standard defines that a Polling device needs to transmit a Deactivation command (e.g., a Listen device needs to receive a Deactivation command). At the time of performing the disconnection of the MFP(CE)-target(W) communication link, the communication target serves as the Polling device and the MFP  10  serves as the Listen device. Therefore, the CPU  30  receives a Deactivation command from the communication target via the NFC I/F  22  and transmits an OK command to the communication target via the NFC I/F  22 . Then, the MFP(CE)-target(W) communication link is disconnected. After the MFP(CE)-target(W) communication link is disconnected, the CPU  30  ends the CE mode and starts the P2P mode. Thus, the MFP  10  starts operating in the P2P mode. The routine proceeds to step S 62  and the CPU  30  performs the P2P mode process (see  FIG. 6 ). As the CPU  30  ends the P2P mode process of step S 62 , the CPU  30  ends the CE mode process. 
     When neither of the MFP(CE)-target(R) communication link and the MFP(CE)-target(W) communication link is established, the CPU  30  makes a negative determination (e.g., NO) in each of steps S 50  and S 54 , and ends the CE mode process. 
     After the CE mode process (e.g.,  FIG. 3  and step S 36  in  FIG. 2 ) ends, the routine returns to step S 10  in  FIG. 2  and the CPU  30  makes a determination in step S 10  again. Thereafter, when the CPU  30  makes a positive determination (e.g., YES) in one of steps S 12 , S 14 , and S 16  in  FIG. 2 , the CPU  30  performs the CE mode process of  FIG. 3  again. 
     Next, referring to  FIG. 4 , further details of the Writer mode process (e.g., step S 40  in  FIG. 2 ) performed by the CPU  30  of the MFP  10  will be described. The Writer mode process is performed by the CPU  30  of the MFP  10  operating in the Writer mode. As the Writer mode process starts, the CPU  30  performs monitoring in one or more of steps S 70  and S 76 . 
     In step S 70 , the CPU  30  monitors establishment of an MFP(W)-target(CE) communication link. When the CPU  30  transmits an Activation command corresponding to the Writer mode to the communication target operating in the CE mode (e.g., the identification card  100 ) and receives an OK command from the communication target, the CPU  30  determines that the MFP(W)-target(CE) communication link has been established. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 70 , and the routine proceeds to step S 72 . 
     In step S 72 , the CPU  30  transmits writing data (e.g., a URL designated by the user or text inputted by the user), included in a writing job stored in the memory  32 , to the communication target (e.g., the identification card  100 ), using the mobile terminal(W)-target(CE) communication link. In step S 74 , the CPU  30  deletes the writing job stored in the memory  32 . Subsequent to step S 74 , the CPU  30  ends the Writer mode process (e.g.,  FIG. 4  and step S 40  in  FIG. 2 ). 
     In step S 76 , the CPU  30  monitors detection of a device operating in the P2P mode. As described above, the MFP  10  operates in the Writer mode. For example, the MFP  10  serves as a Polling device. As further described above, the device operating in the P2P mode performs the Polling operation and the Listen operation repeatedly. Therefore, while the device operating in the P2P mode (hereinafter, referred to as a “particular device”) performs the Listen operation, the particular device receives a polling signal transmitted by the NFC I/F  22  of the MFP  10 . In response to the polling signal, the particular device transmits a response signal to the NFC I/F  22  of the MFP  10 . Upon receipt of the response signal from the particular device, the NFC I/F  22  of the MFP  10  transmits an inquiry signal to inquire in which of the modes does the particular device operate. Upon receipt of the inquiry signal, the particular device transmits an active mode signal indicating that the particular device operates in the P2P mode, to the NFC I/F  22  of the MFP  10 . The NFC I/F  22  of the MFP  10  receives the active mode signal indicating the particular device operates in the P2P mode, from the particular device. The NFC I/F  22  of the MFP  10  passes the active mode signal indicating that the particular device operates in the P2P mode, to the CPU  30 . In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 76 , and the routine proceeds to step S 78 . 
     In step S 78 , the CPU  30  ends the Writer mode and starts the P2P mode. Thus, the MFP  10  starts operating in the P2P mode. The routine proceeds to step S 80  and the CPU  30  performs the P2P mode process (see  FIG. 6 ). After the P2P mode process in step S 80  ends, the CPU  30  ends the Writer mode process. 
     When an MFP(W)-target(CE) communication link is not established and a device operating in the P2P mode is not detected, the CPU  30  makes a negative determination (e.g., NO) in each of steps S 70  and S 76  and ends the Writer mode process. 
     After the Writer mode process (e.g.,  FIG. 4  and step S 40  in  FIG. 2 ) ends, the routine returns to step S 10  in  FIG. 2  and the CPU  30  performs the determination in step S 10  again. Thereafter, when the CPU  30  makes a positive determination (e.g., YES) in step S 16  in  FIG. 2 , the CPU  30  performs the Writer mode process of  FIG. 4  again. 
     Next, referring to  FIG. 5 , a detail of the Reader mode process (e.g., step S 44  of  FIG. 2 ) performed by the CPU  30  of the MFP  10  will be described. The Reader mode process is performed by the CPU  30  of the MFP  10  operating in the Reader mode. As the Reader mode process starts, the CPU  30  performs monitoring in one or more of steps S 90  and S 98 . 
     In step S 90 , the CPU  30  monitors establishment of an MFP(R)-target(CE) communication link. When the CPU  30  transmits an Activation command corresponding to the Reader mode to the communication target operating in the CE mode (e.g., the identification card  100 ) and receives an OK command from the communication target, the CPU  30  determines that an MFP(R)-target(CE) communication link has been established. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 90 , and the routine proceeds to step S 92 . 
     In step S 92 , the CPU  30  receives authentication data from the communication target (e.g., the identification card  100 ) via the NFC I/F  22  using the MFP(R)-target(CE) communication link. In step S 94 , the CPU  30  performs the authentication process using the received authentication data. When the authentication is successful, the CPU  30  allows the printing execution unit  16  to print an image represented by print data included in a print job. As the printing is completed, the routine proceeds to step S 96 . In step S 96 , the CPU  30  deletes the print job from the memory  32 . Subsequent to step S 96 , the CPU  30  ends the Reader mode process (e.g.,  FIG. 5  and step S 44  in  FIG. 2 ). 
     In step S 98 , the CPU  30  monitors detection of a device operating in the P2P mode (e.g., the particular device). As described above, the MFP  10  operates in the Reader mode. That is, the MFP  10  serves as the Polling device. As described above, the particular device operating in the P2P mode performs the Polling operation and the Listen operation repeatedly. Therefore, while the particular device performs the Listen operation, the particular device receives a polling signal transmitted by the NFC I/F  22  of the MFP  10 . Upon receipt of the polling signal, the particular device transmits a response signal to the NFC I/F  22  of the MFP  10 . Upon receipt of the response signal from the particular device, the NFC I/F  22  of the MFP  10  transmits an inquiry signal to inquire in which of the modes does the particular device operate. Upon receipt of the inquiry signal, the particular device transmits an active mode signal indicating that the particular device operates in the P2P mode to the NFC I/F  22  of the MFP  10 . The NFC I/F  22  of the MFP  10  receives, from the particular device, the active mode signal indicating that the particular device operates in the P2P mode. The NFC I/F  22  of the MFP  10  passes the information indicating that the particular device operates in the P2P mode, to the CPU  30 . In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 98  and the routine proceeds to step S 100 . 
     In step S 100 , the CPU  30  ends the Reader mode and starts the P2P mode. Thus, the MFP  10  starts operating in the P2P mode. The routine proceeds to step S 102  and the CPU  30  performs the P2P mode process (see  FIG. 6 ). After the P2P mode process in step S 102  ends, the CPU  30  ends the Reader mode process. 
     When an MFP(R)-target(CE) communication link is not established and a device operating in the P2P mode is not detected, the CPU  30  makes a negative determination (e.g., NO) in each of steps S 90  and S 98  and ends the Reader mode process. 
     As the Reader mode process (e.g.,  FIG. 5  and step S 44  in  FIG. 2 ) ends, the routine returns to step S 10  in  FIG. 2  and the CPU  30  makes the determination in step S 10  again. Thereafter, when the CPU  30  make a positive determination (e.g., YES) in step S 18  in  FIG. 2 , the CPU  30  performs the Reader mode process of  FIG. 5  again. 
     Next, referring to  FIG. 6 , further details of the P2P mode process (e.g., step S 22  in  FIG. 2 , step S 62  in  FIG. 3 , step S 80  in  FIG. 4 , and step S 102  in  FIG. 5 ) performed by the CPU  30  of the MFP  10  will be described. The P2P mode process is performed by the CPU  30  of the MFP  10  operating in the P2P mode. As the P2P mode process starts, the CPU  30  performs monitoring in step S 110 . 
     In step S 110 , the CPU  30  monitors establishment of a P2P communication link. As described above, for example, in a case where the MFP  10  serves as the Polling device, the CPU  30  determines that a P2P communication link has been established when the CPU  30  transmits an Activation command corresponding to the P2P mode to the communication target (e.g., the mobile terminal  50 ) operating in the P2P mode and receives an OK command from the communication target. In this case, the CPU  30  makes a positive determination (e.g., YES) in step S 110  and the routine proceeds to step S 112 . For example, in a case where the MFP  10  serves as the Listen device, the CPU  30  determines that a P2P communication link has been established when the CPU  30  receives an Activation command corresponding to the P2P mode from the communication target (e.g., the mobile terminal  50 ) operating in the P2P mode and transmits an OK command to the communication target. In this case, also, the CPU  30  makes a positive determination (e.g., YES) in step S 110  and the routine proceeds to step S 112 . 
     In step S 112 , the CPU  30  performs two-way communication (hereinafter, referred to as “P2P communication”) with the communication target (e.g., the mobile terminal  50 ) via the NFC I/F  22  using the P2P communication link. More specifically, first, the CPU  30  receives an execution request for an execution of the particular function and network information related to the network to which the communication target belongs, from the communication target. Nevertheless, when the CPU  30  has already been received the execution request from the communication target as of step S 112  (e.g., YES in each of steps S 56  and S 58  in  FIG. 3 ), the CPU  30  does not receive another execution request from the communication target again. The CPU  30  transmits, to the communication target, one of setting information and change-unnecessary information. The setting information includes a wireless setting (e.g., an authentication method, an encryption method, a password, an SSID, and a BSSID) of the network to which the MFP  10  belongs, and the change-unnecessary information indicates that the setting change is unnecessary. The detail of two-way communication performed in step S 112  depends on whether the communication target belongs to a network. Hereinafter, the detail of two-way communication performed in step S 112  will be described for each case. 
     When the communication target belongs to a network, the communication target transmits, to the MFP  10 , an execution request for an execution of a particular function and the wireless setting (e.g., SSID and BSSID) of the network (e.g., a wireless LAN or a WFD network) to which the communication target belongs. Nevertheless, as described above, when the communication target has already transmitted the execution request to the MFP  10  (e.g., YES in step S 56  and YES in step S 58  in  FIG. 3 ), the communication target does not transmit another execution request to the MFP  10  again. The CPU  30  receives the execution request and the wireless setting of the network to which the communication target belongs. In this case, the wireless setting of the network to which the communication target belongs is the “network information” of the communication target. 
     The CPU  30  determines, based on the received wireless setting, whether the MFP  10  belongs to the same network to which the communication target belongs. That is, the CPU  30  determines whether the received SSID and BSSID coincide with an SSID and a BSSID, respectively, included in the wireless setting of the network to which the MFP  10  belongs. When the CPU  30  determines that the MFP  10  belongs to the same network to which the communication target belongs, the CPU  30  transmits, to the communication target, the change-unnecessary information indicating that the setting change is unnecessary. 
     When the CPU  30  determines that the network to which the MFP  10  belongs differs from the network to which the communication target belongs, the CPU  30  transmits a wireless setting (e.g., an authentication method, an encryption method, a password, an SSID, and a BSSID) of a WFD network in which the MFP  10  serves as a group owner, to the communication target. For example, when the MFP  10  belongs to a WFD network, as a group owner, the CPU  30  transmits the wireless setting used in the WFD network to the communication target. For example, when the MFP  10  does not belong to the WFD network in which the MFP  10  serves as a group owner, the CPU  30  changes the status of the MFP  10  to the G/O status and establishes a new WFD network. Then, the CPU  30  transmits a wireless setting of the WFD network to the communication target. 
     When the communication target does not belong to any network, the communication target transmits, to the MFP  10 , an execution request for executing a particular function and information indicating that the communication target does not belong to any network. Nevertheless, also, in this case, when the communication target has already transmitted the execution request to the MFP  10  (e.g., YES in each steps S 56  and S 58  in  FIG. 3 ), the communication target does not transmit another execution request to the MFP  10  again. The CPU  30  receives the execution request and the information indicating that the communication target does not belong to any network. In this case, the information indicating that the communication target does not belong to any network is the “network information” of the communication target. 
     Then, the CPU  30  determines whether the MFP  10  belongs to the WFD network in which the MFP  10  itself serves as a group owner. When the CPU  30  determines that the MFP  10  belongs to the WFD network in which the MFP  10  itself serves as a group owner, the CPU  30  transmits a wireless setting used in the WFD network to the communication target. 
     When the CPU  30  determines that the MFP  10  does not belong to the WFD network in which the MFP  10  itself serves as a group owner, the CPU  30  changes the status of the MFP  10  to the G/O status and establishes a new WFD network. Then, the CPU  30  transmits a wireless setting of the WFD network to the communication target. 
     Through the two-way communication in step S 112 , the wireless setting becomes available for common use in both the MFP  10  and the communication target. The CPU  30  establishes a wireless communication link (e.g., a WFD connection or a basic Wi-Fi connection) between the MFP  10  and the communication target via the wireless LAN I/F  20 , using the common use wireless setting. 
     Then, in step S 114 , the CPU  30  executes the particular function indicated by the execution request. More specifically, in step S 114 , the CPU  30  performs communication of target data to be used to execute the particular function indicated by the execution request, between the MFP  10  and the communication target, via the wireless LAN I/F  20 , using the established wireless communication link. For example, when the particular function is printing, the communication target transmits print data (e.g., target data) to the MFP  10 . Upon receipt of the target data, the CPU  30  allows the printing execution unit  16  to print an image represented by the target data. In another case, for example, when the particular function is scanning, the CPU  30  allows the scanning execution unit  18  to scan one or more documents placed on a document feed mechanism to generate scan data (e.g., target data). The CPU  30  transmits the generated target data to the communication target. 
     Subsequent to step S 114 , the CPU  30  ends the P2P mode process. When a P2P communication link is not established, the CPU  30  makes a negative determination (e.g., NO) in step S 110  and ends the P2P mode process. After the P2P mode process (e.g., step S 22  in  FIG. 2 , step S 62  in  FIG. 3 , step S 80  in  FIG. 4 , and step S 102  in  FIG. 5 ) ends, the routine returns to step S 10  of  FIG. 2  and the CPU  30  performs the determination in step S 10  again. Thereafter, when a negative determination (e.g., NO) is made in step S 18  in  FIG. 2 , when a positive determination (e.g., YES) is made in step S 58  in  FIG. 3 , when a positive determination (e.g., YES) is made in step S 76  in  FIG. 4 , or when a positive determination (e.g., YES) is made in step S 98  in  FIG. 5 , the CPU  30  performs the P2P mode process of  FIG. 6  again. 
     Referring to  FIG. 7 , example communication performed between the MFP  10  and one of the mobile terminals  50  and  80  when the MFP  10  operates in the CE mode will be described below. In  FIG. 7 , two communication examples will be described wherein one example is communication performed between the MFP  10  operating in the CE mode and the mobile terminal  50  operating in the Reader mode, and the other example is communication performed between the MFP  10  operating in the CE mode and the mobile terminal  80  operating in the P2P mode. 
     In the example depicted in  FIG. 7 , after the power of the MFP  10  is turned on, the application URL provision mode setting is changed to “ON” through an operation performed on the operation unit  12 . Thus, the value indicating “ON” of the application URL provision mode setting is stored in the memory  32  of the MFP  10  (e.g., YES in step S 14  in  FIG. 2 ). Therefore, the MFP  10  starts operating in the CE mode (e.g., step S 32  in  FIG. 2 ). Then, the MFP  10  stores the application download URL in the NFC I/F  22  (e.g., step S 34  in  FIG. 2 ). Thereafter, the MFP  10  monitors establishment of one of an MFP(CE)-target(W) communication link and an MFP(CE)-target(R) communication link (e.g., step S 50  or S 54  in  FIG. 3 ). 
     In the example depicted in  FIG. 7 , the application for MFP has not yet been installed on the mobile terminal  50 . When the power of the mobile terminal  50  is turned on, the mobile terminal  50  enters into the initial status in which the Reader mode is active and the other modes are inactive. Then, the mobile terminal  50  monitors establishment of a mobile terminal(R)-target(CE) communication link. 
     As the mobile terminal  50  is brought closer to the MFP  10  under this situation, the NFC I/F  22  of the MFP  10  and the NFC I/F  58  of the mobile terminal  50  come closer to each other so that the NFC I/F  22  and the NFC I/F  58  become communicable to each other (e.g., a distance therebetween is shorter than 10 cm). Thus, an MFP  10  (CE)-mobile terminal  50  (R) communication link is established between the MFP  10  and the mobile terminal  50  via the NFC I/F  22  and the NFC I/F  58  (e.g., YES in step S 50  in  FIG. 3 ). 
     After the MFP  10  (CE)-mobile terminal  50  (R) communication link is established between the MFP  10  and the mobile terminal  50 , the NFC I/F  22  of the MFP  10  transmits the application download URL stored in the NFC I/F  22  to the mobile terminal  50  using the MFP  10  (CE)-mobile terminal  50  (R) communication link. The mobile terminal  50  receives the application download URL. 
     The mobile terminal  50  accesses a server (e.g., a server offered by the vendor of the MFP  10 ) indicated by the application download URL, using the received application download URL, to download the application for MFP. Then, the mobile terminal  50  installs the downloaded application for MFP in the memory  64 . With this installation, the mobile terminal  50  becomes capable of performing various processes in accordance with the application for MFP. 
     The mobile terminal  80  has the application for MFP already installed thereon. As a function execution instruction (e.g., the scanning instruction or the printing instruction) is inputted via the operation portion after the application for MFP starts, the mobile terminal  80  shifts to a state where the P2P mode is active and the other modes are inactive. 
     As the mobile terminal  80  is brought closer to the MFP  10  under this situation, the mobile terminal  80  operating in the P2P mode detects that the MFP  10  is operating in the CE mode. As described above, the mobile terminal operating in the P2P mode performs the Polling operation and the Listen operation repeatedly. The MFP  10  operating in the CE mode serves as a Listen device that performs the Listen operation. When the mobile terminal  80  performs the Polling operation, the mobile terminal  80  transmits a polling signal to the MFP  10  serving as a Listen device. Upon receipt of the polling signal from the mobile terminal  80 , the MFP  10  transmits a response signal to the mobile terminal  80 . Upon receipt of the response signal from the MFP  10 , the mobile terminal  80  transmits an inquiry signal to inquire which of the modes the MFP  10  operates. Upon receipt of the inquiry signal, the MFP  10  transmits an active mode signal indicating that the MFP  10  is operating in the CE mode, to the mobile terminal  80 . Thus, the mobile terminal  80  detects that the MFP  10  is operating in the CE mode. 
     When the mobile terminal  80  detects that the MFP  10  is operating in the CE mode, the mobile terminal  80  ends the P2P mode and starts the Writer mode. Then, the mobile terminal  80  monitors establishment of a mobile terminal(W)-target(CE) communication link. 
     When the MFP  10  and the mobile terminal  80  are present within a range in which the MFP  10  and the mobile terminal  80  can perform NFC communication with each other under the above situation, an MFP  10  (CE)-mobile terminal  80  (W) communication link is established between the MFP  10  and the mobile terminal  80  (e.g., YES in step S 54  in  FIG. 3 ). 
     After the MFP  10  (CE)-mobile terminal  80  (W) communication link is established between the MFP  10  and the mobile terminal  80 , the mobile terminal  80  transmits an execution request for an execution of the particular function to the MFP  10  using the MFP  10  (CE)-mobile terminal  80  (W) communication link. Upon receipt of the execution request, the mobile terminal  80  ends the Writer mode and starts the P2P mode. Then, the mobile terminal  80  monitors establishment of a P2P communication link. 
     The MFP  10  receives the execution request via the NFC I/F  22  (e.g., YES in step S 56  in  FIG. 3 ). Then, the MFP  10  determines whether the particular function indicated by the execution request is executable (e.g., step S 58  in  FIG. 3 ). In the example depicted in  FIG. 7 , the MFP  10  determines that the particular function is executable (e.g., YES in step S 58  in  FIG. 3 ). Then, the MFP  10  ends the CE mode and starts the P2P mode (e.g., step S 60  in  FIG. 3 ). Thus, the MFP  10  and the mobile terminal  80  disconnect the MFP  10  (CE)-mobile terminal  80  (W) communication link. Then, the MFP  10  monitors establishment of a P2P communication link (e.g., step S 110  in  FIG. 6 ). 
     When the MFP  10  and the mobile terminal  80  are present within a range in which the MFP  10  and the mobile terminal  80  can perform NFC communication with each other under the above situation, a P2P communication link is established between the MFP  10  and the mobile terminal  80  (e.g., YES in step S 110  in  FIG. 6 ). Then, P2P communication is performed between the MFP  10  and the mobile terminal  80  using the P2P communication link (e.g., step S 112  in  FIG. 6 ). For example, the mobile terminal  80  transmits network information (e.g., the wireless setting of the network to which the mobile terminal  80  belongs or the information indicating that the mobile terminal  80  does not belong to any network) to the MFP  10 . In the example depicted in  FIG. 7 , the mobile terminal  80  has already transmitted the execution request to the MFP  10  and the mobile terminal  80  therefore does not transmit another execution request to the MFP  10  at this time. Next, the MFP  10  transmits one of the wireless setting of the WFD network in which the MFP  10  itself serves as the group owner and the change-unnecessary information to the mobile terminal  80 . According to this configuration, the MFP  10  may change the operation mode of the MFP  10  from the CE mode to the P2P mode appropriately. Therefore, the MFP  10  may perform P2P communication appropriately with the mobile terminal  80  using the P2P communication link. 
     Through the P2P communication, the wireless setting becomes available for common use in both the MFP  10  and the mobile terminal  80 . The MFP  10  and the mobile terminal  80  establish a wireless communication link (e.g., a WFD connection or a basic Wi-Fi connection) therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80 , using the common use wireless setting. 
     Then, the MFP  10  and the mobile terminal  80  perform communication of target data, to be used to execute the particular function indicated by the execution request, therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80 , using the established wireless communication link (e.g., step S 114  in  FIG. 6 ). For example, when the particular function is printing, the mobile terminal  80  transmits print data (e.g., target data) to the MFP  10 . Upon receipt of the target data, the MFP  10  allows the printing execution unit  16  to print an image represented by the target data. When the particular function is scanning, the CPU  30  allows the scanning execution unit  18  to scan one or more documents placed on the document feed mechanism to generate scan data (e.g., target data). The MFP  10  transmits the generated target data to the mobile terminal  80 . 
     After the execution of the particular function is completed, the mobile terminal  80  ends the running application for MFP. 
     Referring to  FIG. 8 , example communication performed between the MFP  10  and one of the identification card  100  and the mobile terminal  80  when the MFP  10  operates in the Writer mode will be described. In  FIG. 8 , two communication examples will be described wherein one example is communication performed between the MFP  10  operating in the Writer mode and the identification card  100  operating in the CE mode and the other example is communication performed between the MFP  10  operating in the Writer mode and the mobile terminal  80  operating in the P2P mode. 
     In the example depicted in  FIG. 8 , after the power of the MFP  10  is turned on, the MFP  10  receives a writing job from the PC  8  via the AP  6 . The MFP  10  stores the received writing job in the memory  32  (e.g., YES in step S 16  in  FIG. 2 ). Thus, the MFP  10  starts operating in the Writer mode (e.g., step S 38  in  FIG. 2 ). Then, while monitoring establishment of an MFP(W)-target(CE) communication link (e.g., step S 70  in  FIG. 4 ), the MFP  10  monitors detection of a device operating in the P2P mode (e.g., step S 76  in  FIG. 4 ). 
     In some arrangements, the identification card  100  operates in the CE mode at all times. Accordingly, as the identification card  100  is brought closer to the MFP  10 , an MFP  10  (W)-identification card  100  (CE) communication link is established between the MFP  10  and the identification card  100  (e.g., YES in step S 70  in  FIG. 4 ). 
     After the MFP  10  (W)-identification card  100  (CE) communication link is established between the MFP  10  and the identification card  100 , the MFP  10  transmits writing data (e.g., the URL designated by the user and/or text inputted by the user) included in the writing job stored in the memory  32  to the identification card  100  using the MFP  10  (W)-identification card  100  (CE) communication link (e.g., step S 72  in  FIG. 4 ). The identification card  100  receives the writing data and stores the received writing data therein. 
     After transmitting the writing data, the MFP  10  deletes the writing job from the memory  32  (e.g., step S 74  in  FIG. 4 ). 
     In the example depicted in  FIG. 8 , the mobile terminal  80  has the application for MFP already installed thereon. As a function execution instruction (e.g., the scanning instruction or the printing instruction) is inputted via the operation portion after the application for MFP starts, the mobile terminal  80  starts operating in the P2P mode. 
     As the mobile terminal  80  is brought closer to the MFP  10  under this situation, the MFP  10  operating in the Writer mode detects that the mobile terminal  80  is operating in the P2P mode. The MFP  10  operating in the Writer mode serves as a Polling device that performs the Polling operation. The mobile terminal  80  operating in the P2P mode performs the Polling operation and the Listen operation repeatedly. While the mobile terminal  80  performs the Listen operation, the mobile terminal  80  receives a polling signal transmitted by the MFP  10  serving as the Polling device. Upon receipt of the polling signal, the mobile terminal  80  transmits a response signal to the MFP  10 . Upon receipt of the response signal from the mobile terminal  80 , the MFP  10  transmits an inquiry signal to inquire in which of the modes the mobile terminal  80  operates. Upon receipt of the inquiry signal, the mobile terminal  80  transmits an active mode signal indicating that the mobile terminal  80  is operating in the P2P mode, to the MFP  10 . Thus, the MFP  10  may detect that the mobile terminal  80  is operating in the P2P mode (e.g., YES in step S 76  in  FIG. 4 ). 
     When the MFP  10  detects the mobile terminal  80  operating in the P2P mode, the MFP  10  ends the Writer mode and starts the P2P mode (e.g., step S 78  in  FIG. 4 ). Then, the MFP  10  monitors establishment of a P2P communication link (e.g., step S 110  in  FIG. 6 ). 
     When the MFP  10  and the mobile terminal  80  are present within a range in which the MFP  10  and the mobile terminal  80  can perform NFC communication with each other under the above situation, a P2P communication link is established between the MFP  10  and the mobile terminal  80  (e.g., YES in step S 110  in  FIG. 6 ). Then, P2P communication is performed between the MFP  10  and the mobile terminal  80  using the P2P communication link (e.g., step S 112  in  FIG. 6 ). For example, the mobile terminal  80  transmits, to the MFP  10 , an execution request for requesting execution of the particular function and network information (e.g., one of the wireless setting of the network to which the mobile terminal  80  belongs and the information indicating that the mobile terminal  80  does not belong to any network). Then, the MFP  10  transmits, to the mobile terminal  80 , a wireless setting of the WFD network in which the MFP  10  itself serves as a group owner and the change-unnecessary information. According to this configuration, the MFP  10  may change the operation mode of the MFP  10  from the Writer mode to the P2P mode appropriately. Therefore, the MFP  10  may perform P2P communication with the mobile terminal  80  appropriately using the P2P communication link. 
     Through the P2P communication, the wireless setting becomes available for common use in both the MFP  10  and the mobile terminal  80 . The MFP  10  and the mobile terminal  80  establish a wireless communication link (e.g., a WFD connection or a basic Wi-Fi connection) therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80  using the common use wireless setting. 
     Then, the MFP  10  and the mobile terminal  80  perform communication of target data to be used to execute the particular function indicated by the execution request, therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80 , using the established wireless communication link (e.g., step S 114  in  FIG. 6 ). For example, when the particular function is printing, the mobile terminal  80  transmits print data (e.g., target data) to the MFP  10 . Upon receipt of the target data, the MFP  10  allows the printing execution unit  16  to print an image represented by the target data. When the particular function is scanning, the MFP  10  allows the scanning execution unit  18  to scan one or more documents placed on the document feed mechanism to generate scan data (e.g., target data). The MFP  10  transmits the generated target data to the mobile terminal  80 . 
     After the execution of the particular function is completed, the mobile terminal  80  ends the running application for MFP. 
     Referring to  FIG. 9 , example communication performed between the MFP  10  and one of the identification card  100  and the mobile terminal  80  when the MFP  10  operates in the Reader mode will be described. In  FIG. 9 , two communication examples will be described wherein one example is communication performed between the MFP  10  operating in the Reader mode and the identification card  100  operating in the CE mode and the other example is communication performed between the MFP  10  operating in the Reader mode and the mobile terminal  80  operating in the P2P mode. 
     In the example depicted in  FIG. 9 , after the power of the MFP  10  is turned on, the MFP  10  receives a print job from the PC  8  via the AP  6 . The MFP  10  stores the received print job in the memory  32  (e.g., YES in step S 18  in  FIG. 2 ). Thus, the MFP  10  starts operating in the Reader mode (e.g., step S 42  in  FIG. 2 ). Then, while monitoring establishment of an MFP(R)-target(CE) communication link of the MFP  10  (e.g., step S 90  in  FIG. 5 ), the MFP  10  monitors detection of a device operating in the P2P mode (e.g., step S 98  in  FIG. 5 ). 
     As described above, the identification card  100  operates in the CE mode at all times. As the identification card  100  is brought closer to the MFP  10 , an MFP  10  (R)-identification card  100  (CE) communication link is established between the MFP  10  and the identification card  100  (e.g., YES in step S 90  in  FIG. 5 ). 
     After the MFP  10  (R)-identification card  100  (CE) communication link is established between the MFP  10  and the identification card  100 , the MFP  10  receives, from the identification card  100 , authentication data stored in the identification card  100 , using the MFP  10  (R)-identification card  100  (CE) communication link (e.g., step S 92  in  FIG. 5 ). 
     Then, the MFP  10  performs the authentication process using the received authentication data (e.g., step S 94  in  FIG. 5 ). In the example depicted in  FIG. 9 , authentication succeeds. After successful authentication, the MFP  10  allows the printing execution unit  16  to print an image represented by print data included in the print job. After the printing is completed, the MFP  10  deletes the print job from the memory  32  (e.g., step S 96  in  FIG. 5 ). 
     In the example depicted in  FIG. 9 , the mobile terminal  80  has the application for MFP already installed thereon. As a function execution instruction (e.g., the scanning instruction or the printing instruction) is inputted via the operation portion after the application for MFP starts, the mobile terminal  80  starts operating in the P2P mode. 
     As the mobile terminal  80  is brought closer to the MFP  10  under this situation, the MFP  10  operating in the Reader mode detects that the mobile terminal  80  is operating in the P2P mode. The MFP  10  operating in the Reader mode serves as a Polling device that performs the Polling operation. The mobile terminal  80  operating in the P2P mode performs the Polling operation and the Listen operation repeatedly. While the mobile terminal  80  performs the Listen operation, the mobile terminal  80  receives a polling signal transmitted by the MFP  10  serving as the Polling device. Upon receipt of the polling signal, the mobile terminal  80  transmits a response signal to the MFP  10 . Upon receipt of a response signal from the mobile terminal  80 , the MFP  10  transmits an inquiry signal to inquire in which of the modes does the mobile terminal  80  operate. Upon receipt of the inquiry signal, the mobile terminal  80  transmits an active mode signal indicating that the mobile terminal  80  is operating in the P2P mode, to the MFP  10 . Thus, the MFP  10  may detect that the mobile terminal  80  is operating in the P2P mode (e.g., YES in step S 98  in  FIG. 5 ). 
     When the MFP  10  detects the mobile terminal  80  operating in the P2P mode, the MFP  10  ends the Reader mode and starts the P2P mode (e.g., step S 100  in  FIG. 5 ). Then, the MFP  10  monitors establishment of a P2P communication link (e.g., step S 110  in  FIG. 6 ). 
     When the MFP  10  and the mobile terminal  80  are present within a range in which the MFP  10  and the mobile terminal  80  can perform NFC communication with each other under the above situation, a P2P communication link is established between the MFP  10  and the mobile terminal  80  (e.g., YES in step S 110  in  FIG. 6 ). Then, P2P communication is performed between the MFP  10  and the mobile terminal  80  using the P2P communication link (e.g., step S 112  in  FIG. 6 ). The P2P communication performed here is the same as the P2P communication performed in the example depicted in  FIG. 8 , and therefore, a detailed description will be omitted. According to this configuration, the MFP  10  may change the operation mode of the MFP  10  from the Reader mode to the P2P mode appropriately. Therefore, the MFP  10  may perform P2P communication with the mobile terminal  80  appropriately using the P2P communication link. 
     Through the P2P communication, the wireless setting becomes available for common use in both the MFP  10  and the mobile terminal  80 . Similar to the example depicted in  FIG. 8 , the MFP  10  and the mobile terminal  80  establish a wireless communication link (e.g., a WFD connection or a basic Wi-Fi connection) therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80 , using the common use wireless setting. Then, the MFP  10  and the mobile terminal  80  perform communication of target data to be used to execute the particular function indicated by the execution request therebetween via the wireless LAN I/F  20  and the wireless LAN I/F of the mobile terminal  80 , using the established wireless communication link (e.g., step S 114  in  FIG. 6 ). Details of this communication is also the same as the communication performed in the example depicted in  FIG. 8 , and therefore, a detailed description for this communication will be omitted. 
     After the execution of the particular function is completed, the mobile terminal  80  ends the running application for MFP. 
     Referring to  FIG. 10 , example communication performed between the MFP  10  and the mobile terminal  50  operating in the P2P mode when the MFP  10  operates in the P2P mode will be described. 
     In the example depicted in  FIG. 10 , after the power of the MFP  10  is turned on, the MFP  10  operates in the P2P mode (e.g., NO in step S 18 , and step S 20  in  FIG. 2 ). The MFP  10  monitors establishment of a P2P communication link (e.g., step S 110  in  FIG. 6 ). 
     In the example depicted in  FIG. 10 , the mobile terminal  50  has the application for MFP already installed thereon. As a function execution instruction (e.g., the scanning instruction or the printing instruction) is inputted via the operation portion after the application for MFP starts, the mobile terminal  50  shifts to a state where the P2P mode is active and the other modes are inactive. 
     As the mobile terminal  50  is brought closer to the MFP  10  under this situation, a P2P communication link is established between the MFP  10  and the mobile terminal  50  (e.g., YES in step S 110  in  FIG. 6 ). Then, P2P communication is performed between the MFP  10  and the mobile terminal  50  using the P2P communication link (e.g., step S 112  in  FIG. 6 ). The P2P communication performed in this case is the same as the P2P communication performed in the examples depicted in  FIGS. 8 and 9 , and therefore, a detailed description for the P2P communication will be omitted. 
     Through the P2P communication, the wireless setting becomes available for common use in both the MFP  10  and the mobile terminal  50 . Similar to the examples depicted in  FIGS. 8 and 9 , the MFP  10  and the mobile terminal  50  establish a wireless communication link (e.g., a WFD connection or a basic Wi-Fi connection) therebetween via the wireless LAN I/F  20  and the wireless LAN I/F  56 , using the common use wireless setting. Then, the MFP  10  and the mobile terminal  50  perform communication of target data to be used to execute the particular function indicated by the execution request therebetween via the wireless LAN I/F  20  and the wireless LAN I/F  56 , using the established wireless communication link (e.g., step S 114  in  FIG. 6 ). Details of this communication is also the same as the communication performed in the example depicted in  FIGS. 8 and 9 , and therefore, a detailed description for this communication will be omitted. 
     After the execution of the particular function is completed, the mobile terminal  50  ends the running application for MFP. 
     Effects of the illustrative embodiment will be described below. As described with reference to  FIG. 2 , in the illustrative embodiment, when it is determined that the MFP  10  is in the state where the MFP  10  needs to transmit the URL (e.g., the support page URL, the consumable item URL, or the application download URL) (e.g., when a device error has occurred, when a consumable item error has occurred, or when the application URL provision mode is enabled) (e.g., YES in step S 10 , YES in step S 12 , or YES in step S 14  in  FIG. 2 ), the MFP  10  is allowed to operate in the CE mode (e.g., in step S 24 , S 28 , or S 32 ). As depicted in  FIG. 7 , when the MFP  10  (CE)-mobile terminal  50  (R) communication link is established between the MFP  10  operating in the CE mode and the mobile terminal  50  operating in the Reader mode (e.g., YES in step S 50  in  FIG. 3 ), the NFC I/F  22  of the MFP  10  transmits the URL to the mobile terminal  50  using the MFP  10  (CE)-mobile terminal  50  (R) communication link. When it is determined that the MFP  10  is not in the state where the MFP  10  needs to transmit the URL (e.g., NO in step S 10 , NO in step S 12 , and NO in step S 14  in  FIG. 2 ), the MFP  10  is allowed to operate in one of the operation modes (e.g., the P2P mode, the Writer mode, and the Reader mode) other than the CE mode (e.g., step S 20 , S 38 , or S 42 ). The MFP  10  performs an appropriate process in accordance with the operation mode (see  FIGS. 7 to 10 ). That is, the MFP  10  according to the illustrative embodiment may operate in an appropriate operation mode depending on the determination as to whether the MFP  10  is in the state where the MFP  10  needs to transmit the URL. Thus, the MFP  10  may perform appropriate communication with an external device (e.g., one of the mobile terminals  50  and  80  and the identification card  100 ). Therefore, the MFP  10  according to the illustrative embodiment may operate appropriately in accordance with the state of the MFP  10 . 
     The MFP  10  may be an example of a “communication device”. The mobile terminals  50  and  80  may be an example of a “first external device”, a “third external device”, and/or a “fourth external device”. Each of the mobile terminals  50  and  80  and the identification card  100  may be an example of a “second external device”. Each of the P2P mode, the Reader mode, and the Writer mode may be an example of a “first mode”. Each of the P2P mode and the CE mode may be an example of a “second mode”. The URL (e.g., one of the support page URL, the consumable item URL, and the application download URL) may be an example of “pre-stored data”. Each of the execution request, the network information of the mobile terminal  50  ( 80 ), the wireless setting transmitted by the MFP  10 , and the change-unnecessary information transmitted by the MFP  10  may be an example of “first data”. The authentication data (see  FIG. 9 ) may be an example of “second data”. The writing data (see  FIG. 8 ) may be an example of “third data”. Each of the state where a device error has occurred (e.g., YES in step S 10  in  FIG. 2 ), the state where a consumable item error has occurred (e.g., YES in step S 12  in  FIG. 2 ), and the state where the application URL provision mode is enabled (e.g., YES in step S 14  in  FIG. 2 ) may be an example of a “first state”. The state where there is a print job (e.g., YES in step S 18  in  FIG. 2 ) may be an example of a “second state”. The state where there is a writing job (e.g., YES in step S 16  in  FIG. 2 ) may be an example of a “third state”. The MFP  10  (CE)-mobile terminal  50  (R) communication link (see  FIG. 7 ) may be an example of a “first type of communication link”. Each of the MFP  10  (P2P)-mobile terminal  50  (P2P) communication link (see  FIG. 10 ), the MFP  10  (R)-authentication card (CE) communication link (see  FIG. 9 ), and the MFP(W)-mobile terminal(CE) communication link (see  FIG. 8 ) may be an example of a “second type of communication link”. The MFP  10  (P2P)-mobile terminal  80  (P2P) communication link (see  FIGS. 9 and 8 ) may be an example of a “third type of communication link”. The MFP  10  (CE)-mobile terminal  80  (W) communication link (see  FIG. 7 ) may be an example of a “fourth type of communication link”. The MFP  10  (P2P)-mobile terminal  50  (P2P) communication link (see  FIG. 7 ) may be an example of a “fifth type of communication link”. The case where a positive determination (e.g., YES) is made in step S 110  in  FIG. 6  may be an example of a “first case”. The case where a positive determination (e.g., YES) is made in step S 90  in  FIG. 5  may be an example of a “second case”. The case where a positive determination (e.g., YES) is made in step S 70  in  FIG. 4  may be an example of a “third case”. 
     The processing performed in each of steps S 10 , S 12 , and S 14  in  FIG. 2  may be an example of processing performed by a “first determination portion”. The processing performed in step S 18  in  FIG. 2  may be an example of processing performed by a “second determination portion”. The processing performed in step S 16  in  FIG. 2  may be an example of processing performed by a “third determination portion”. The processing performed in each of steps S 24 , S 28 , S 32 , S 20 , S 38 , and S 42  in  FIG. 2  may be an example of processing performed by a “mode setting portion”. The processing performed when a positive determination (e.g., YES) is made in step S 50  in  FIG. 2  may be an example of processing performed by a “transmission portion”. The processing performed in each of steps S 72  in  FIG. 4 , S 92  in  FIG. 5 , and S 112  in  FIG. 6  may be an example of processing performed by a “first communication control portion”. The processing performed in each of steps S 60  in  FIG. 3 , step S 78  in  FIG. 4 , and S 100  in  FIG. 5  may be an example of processing performed by a “changing portion”. The processing performed in step S 56  in  FIG. 3  may be an example of processing performed by a “reception portion”. The processing performed in step S 112  in  FIG. 6  may be an example of processing performed by a “second communication control portion”. The processing performed in step S 112  in  FIG. 6  may be an example of processing performed by a “third communication control portion”. 
     Various embodiments of the disclosure have been described above; however, such embodiments are only examples and do not limit the scope of the appended claims. Examples of the modification and alternations of the above-described embodiment are described below. 
     In other embodiments, for example, the CPU  30  of the MFP  10  may make a determination in each of steps S 10 , S 12 , S 14 , S 16 , and S 18  in  FIG. 2  in order other than the order (e.g., in the order of steps S 10 , S 12 , S 14 , S 16 , and S 18 ) depicted in  FIG. 2 . For example, the first determination portion may be configured to determine whether the communication device is in the first state where the communication device needs to transmit, to the outside such as an external destination, the particular data pre-stored in the communication device. The second determination portion may be configured to determine whether the communication device is in the second state that differs from the first state. The third determination portion may be configured to determine whether the communication device is in the third state that differs from the first state. 
     In other embodiments, for example, the CPU  30  of the MFP  10  may omit one or both of steps S 16  and S 18  in  FIG. 2  so long as the CPU  30  of the MFP  10  performs the determination in each of steps S 10 , S 12 , and S 14  in  FIG. 2 . That is, generally speaking, the mode setting portion may be configured to set the operation mode of the communication device to the CE mode of the NFC standard when it is determined that the communication device is in the first state, and to set the operation mode of the communication device to the first mode of the NFC standard that differs from the CE mode when it is determined that the communication device is not in the first state. 
     In other embodiments, for example, the CPU  30  of the MFP  10  may perform the determination in at least one of steps S 10 , S 12 , and S 14  in  FIG. 2 . In this case, the CPU  30  may omit one or more of steps S 10 , S 12 , and S 14  in  FIG. 2 . That is, generally speaking, the first determination portion may be configured to determine whether the communication device is in the first state where the communication device needs to transmit, to the outside, the particular data pre-stored in the communication device. 
     In the illustrative embodiment, when the communication target (e.g., the mobile terminal  50 ) has already transmitted the execution request to the MFP  10  (e.g., YES in both steps S 56  and S 58  in  FIG. 3 ), the communication target does not transmit another execution request to the MFP  10  in P2P communication performed in step S 112  in  FIG. 6 . Instead of this, in other embodiments, for example, in P2P communication performed in step S 112  of  FIG. 6 , the communication target may be configured to transmit another execution request to the MFP  10  even when the communication target has already transmitted the execution request to the MFP  10 . 
     The technique by which the CPU  30  of the MFP  10  receives a print job or a writing job is not limited to the technique by which the CPU  30  of the MFP  10  receives the print job or the writing job via the AP  6 . In other embodiments, for example, the user may input one of a print job and a writing job directly in the MFP  10  by operating the operation unit  12 . In this case, the CPU  30  of the MFP  10  may be configured to store the one of the print job and the writing job inputted through the operation unit  12  in the memory  32 . Generally speaking, the “third data” may be obtained by the communication device only. 
     The “communication device” is not limited to a multifunction device that is configured to perform the printing function and the scanning function (e.g., the MFP  10 ). In other embodiments, for example, the “communication device” may be a printer that may be configured to perform the printing function only or a scanner that may be configured to perform the scanning function only. The “communication device” may be a device (e.g., a PC, a server, a mobile terminal (e.g., a mobile phone, a smartphone, and a PDA)) that may be configured to perform one or more functions (e.g., an image displaying function or a data calculating function) other than the printing function and the scanning function. That is, the “communication device” may include any device that may be capable of performing communication using the NFC system. The “external device” is also not limited to the mobile terminals  50  and  80  and the identification card  100 , but may include any device that may be capable of performing communication using the NFC system. 
     In the illustrative embodiment, the processing in all steps depicted in  FIGS. 2 to 6  is implemented by software (e.g., the program). Nevertheless, in other embodiments, for example, the processing in at least one of the steps is implemented by hardware, for example, a logical circuit. 
     Further, the technical elements described in the specification and the drawings exhibit technical usability alone or in various combinations, and are not limited to those in the claims at the time of the application of the disclosure. Furthermore, the techniques described as examples in the specification or drawings may achieve a plurality of objects simultaneously, and has technical utility by achieving any one of these objects.