# Patent

## Title
Host device and slave device controlling method

## Abstract

A host device is provided, which includes a network communication unit connected to network; a local communication unit locally connected to a slave device; a virtualization unit to virtualize the slave device as a network device within the network; and a controlling unit to control the virtualized slave device as the network device. Therefore, a developer may implement an application in consideration of a single type of network without considering various physical input and output ports.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 12/659,218, filed on Mar. 1, 2010, which is currently pending, and claims the benefit of Korean Patent Application No. 10-2009-0076287, filed in the Korean Intellectual Property Office on Aug. 18, 2009, the disclosures of each of which are incorporated herein by reference.


BACKGROUND
1. Field
Aspects of the present invention relate to a host device and a slave device controlling method, and more particularly, to a host device which virtualizes a slave device connected to the host device locally and controls the slave device in a method of controlling a network device and a slave device controlling method.
2. Description of the Related Art
Generally, a host device is connected to a slave device through various connection channels such as a serial, a universal serial bus (USB), and Ethernet, and provides a user with various applications through the slave device being connected to the host device.
Applications provided from a host device should be implemented to comply with physical characteristics of the slave device connected to the host device and various communication protocols on the physical layer.
Accordingly, the developer of applications of a host device needs to develop applications that comply with driver software for the connection of various physical layers on the host device and various communication protocols that exist beyond the physical layers.
However, a developer has difficulty in implementing applications because the developer should consider various physical input and output ports since the recent host devices are capable of being connected to various types of slave devices. In addition, the host devices have poor compatibility between applications which drive different types of slave devices.
SUMMARY
Aspects of the present embodiment relate to a host device which virtualizes a slave device connected to the host device via a local loop and controls the slave device in a method of controlling a network device and a slave device controlling method.
Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.
The foregoing and/or other aspects are achieved by providing a host device, including a network communication unit connected to a network; a local communication unit locally connected to a slave device; a virtualization unit to virtualize the slave device as a network device within the network; and a controlling unit to control the virtualized slave device as the network device.
The virtualization unit may include a determination unit to identify a communication protocol of the slave device; a message conversion unit to convert a message of the controlling unit and a message of the slave device into a message which complies with a communication protocol of the slave device and a message which complies with a communication protocol of the network device, respectively, according to the identified communication protocol; and a message transmission unit to transmit the message converted by the message conversion unit to a destination of the message.
The message conversion unit may analyze the message of the controlling unit and the message of the slave device and convert the messages to correspond to the analyzed result.
The virtualization unit may further include an Internet Protocol (IP) address generation unit to allocate an IP address to the slave device when the slave device is connected to the host device.
When the message of the slave device is received from an external network device connected to the network, the controlling unit may control the virtualization unit to convert the received message into a message which complies with the communication protocol of the slave device and transmit the converted message to the slave device.
The message transmission unit may control the network communication unit to transmit the converted message of the slave device to the external network device.
The communication protocol of the network device may be a universal plug-and-play (UPnP) communication protocol.
The slave device may be connected to the host device in at least one of a universal serial bus (USB) communication protocol, an IEEE 1394 communication protocol, a Serial Peripheral Interface (SPI) communication protocol, and a High-Definition Multimedia Interface (HDMI) communication protocol.
The foregoing and/or other aspects are achieved by providing a method to control a slave device locally connected to a host device via network, the slave device controlling method including virtualizing the slave device as a network device within the network; and controlling the virtualized slave device as the network device.
The virtualizing may include allocating an IP address to the slave device when the slave device is connected to the host device; and identifying a communication protocol of the slave device.
The controlling may include converting a message of the host device and a message of the slave device into a message which complies with a communication protocol of the slave device and a message which complies with a communication protocol of the network device, respectively, according to the identified communication protocol; and transmitting the converted message to a destination of the message.
The converting may analyze the message of the host device and the message of the slave device and convert the messages to correspond to the analyzed result.
When the message of the slave device is received from an external network device connected to the network, the controlling may convert the received message into a message which complies with the communication protocol of the slave device and transmit the converted message to the slave device.
The controlling may transmit the converted message of the slave device to the external network device.
The communication protocol of the network device may be a universal plug-and-play (UPnP) communication protocol.
The slave device may be connected to the host device in at least one of a universal serial bus (USB) communication protocol, an IEEE 1394 communication protocol, a Serial Peripheral Interface (SPI) communication protocol, and a High-Definition Multimedia Interface (HDMI) communication protocol.
The foregoing and/or other aspects are achieved by providing a slave device controlling method, including: converting a message at a host device connected to the slave device via a network from a first communication protocol to a second communication protocol so that the slave device is virtualized as a network device of the network.
The first communication protocol may be a communication protocol of the network device and the second communication protocol may be a communication protocol of the slave device, and the message may be converted from the first communication protocol of the network device into the second communication protocol of the slave device and transmitted to the slave device.
The first communication protocol may be a communication protocol of the slave device and the second communication protocol may be a communication protocol of the network device, and the message may be received from the slave device and converted from the first communication protocol of the slave device into the second communication protocol of the network device.
The host device may receive the message from an external network device, convert the message from a first communication protocol of the external network device into a second communication protocol of the slave device and transmit the converted message to the slave device.



BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which:
FIG. 1 is a block diagram of a host device according to an exemplary embodiment;
FIGS. 2 to 5 are views provided to explain a virtualization of a host device; and
FIG. 6 is a flowchart of the process of controlling a slave device according to an exemplary embodiment.



DETAILED DESCRIPTION
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below, in order to explain the present invention by referring to the figures.
FIG. 1 is a block diagram of a host device according to an exemplary embodiment.
Referring to FIG. 1, the host device 100 includes a user interface 110, a storage unit 120, a network communication unit 130, a local communication unit 140, a virtualization unit 150, and a controlling unit 160. The host device 100 may provide a user with an application (service), and may be a personal computer (PC), a laptop computer, a television (TV), or a set-top box (STB), for example.
The user interface 110 includes a plurality of function keys so that a user may set or select various functions supported by the host device 100, and may display various information provided by the host device 100. The user interface 110 may be configured with a device, such as a touch pad, which simultaneously executes input and output operations, or a device combining a mouse with a monitor, for example. Accordingly, a user may use various application services supported by the host device 100 through the user interface 110.
The storage unit 120 may store content corresponding to various services supported by the host device 100, and protocol information of a slave device 200 which will be described later and an Internet Protocol (IP) address for the slave device 200. The storage unit 120 may be an internal storage medium of the host device 100, or an external storage medium, for example, a removable disk including a USB memory, a storage medium being connected to a host, and a web server over a network.
The network communication unit 130 may be connected to a network. In more detail, the network communication unit 130 may be connected to an external network device 300 via the network, and transceive a message to and from the external network device 300 according to a communication protocol of the external network device 300. The network communication unit 130 may be connected to the network by any suitable type of wired or wireless link. In this exemplary embodiment, the communication protocol of the network device may be a universal plug-and-play (UPnP) communication protocol, and the external network device 300 is another host device connected to the network which transceives a message to and from the host device 100 according to a network communication protocol.
Herein, the message may include various controlling commands between the host device 100, the slave device 200, and the network device 300, and a response signal for the controlling commands, and may be, for example, a service request, a state request, and a service providing signal in response to a service request.
The local communication unit 140 is connected to the slave device 200 via a local loop. Specifically, the local communication unit 140 is connected to the slave device 200 via a local loop, and transceives a message to and from the slave device 200 according to a communication protocol of the slave device 200. For example, if the slave device 200 is a USB device, the local communication unit 140 may transceive a message to and from the USB device according to a USB communication protocol, and if the slave device 200 is an Institute of Electrical and Electronics Engineers (IEEE) 1394 device, the local communication unit 140 may transceive a message to and from the IEEE 1394 device according to an IEEE 1394 communication protocol. The communication protocol of the slave device 200 may include a USB communication protocol, an IEEE 1394 communication protocol, a High-Definition Multimedia Interface (HDMI) communication protocol, a serial communication protocol, and a parallel communication protocol, for example. In this exemplary embodiment, the slave device 200 may be directly connected to the host device 100 according to at least one of a USB communication protocol, an IEEE 1394 communication protocol, a Serial Peripheral Interface (SPI) communication protocol, and a HDMI communication protocol, for example, to provide a user with a service.
The virtualization unit 150 virtualizes the slave device 200 as a network device within the network. In more detail, the virtualization unit 150 includes a determination unit 151, a message conversion unit 152, a message transmission unit 153, and an Internet Protocol (IP) address generation unit 154. The virtualization allows the slave device 200 to operate like a network device connected to the network by generating a virtual network device.
The determination unit 151 may determine a communication protocol of the slave device 200. Specifically, the determination unit 151 may recognize information required to communicate with the slave device 200, such as the type of the slave device 200 and the communication protocol. For example, if the slave device 200 connected to the host device 100 is a USB memory, the determination unit 151 may recognize that the corresponding slave device is a USB memory that communicates with the host device 100 according to a USB communication protocol, using a PnP communication protocol. In addition, the determination unit 151 may store the recognized information regarding the slave device 200 in the storage unit 120.
The message conversion unit 152 may convert the message of the controlling unit 160 and the message of the slave device 200 into a message which complies with the communication protocol of the slave device 200 and a message which complies with the communication protocol of the network device, respectively, according to the identified communication protocol of the slave device 200. Specifically, the message conversion unit 152 may convert the message of the slave device 200 into a message which complies with the communication protocol of the network device, and convert the message of the controlling unit 160 or the message of the external network device 300 into a message which complies with the communication protocol of the slave device 200.
The message conversion unit 152 may analyze the message of the controlling unit 160 and the message of the slave device 200, and convert the messages into messages corresponding to the analyzed result. In more detail, the message conversion unit 152 may analyze the messages between the slave device 200 and the host device 100 as well as the communication protocol of the slave device 200 and the communication protocol of the network device, and convert the messages into messages corresponding to the analyzed result. An algorithm or a look-up table related to the analysis of the messages may be stored in the storage unit 120. Accordingly, a developer may develop an application without considering a message standardization of the slave device 200. For example, if Message 1 indicates a power-off operation of the slave device 200, the message conversion unit 152 interprets the message indicating the power-off operation of the slave device 200 as Message 1 using the pre-stored algorithm or look-up table, and converts Message 1 into a message complying with the communication protocol of the slave device 200. On the other hand, if Message 1 is received from the slave device 200, the message conversion unit 152 analyzes Message 1 as the message indicating the power-off operation of the slave device 200 using the pre-stored algorithm or look-up table, and converts the message indicating the power-off operation into a message complying with the communication protocol of the network device.
The message transmission unit 153 may transmit the message which is converted by the message conversion unit 152 to the destination of the message. Specifically, the message transmission unit 153 may transmit the message, which is converted by the message conversion unit 152 to be suitable for the destination of the message transmitted to the virtualization unit 150, to the controlling unit 160 or the slave device 200. For example, if the virtualization unit 150 receives a message to be transmitted to the slave device 200 from the controlling unit 160, the message transmission unit 153 may control the local communication unit 140 to transmit the message which is converted by the message conversion unit 152 to the slave device 200. On the other hand, if the virtualization unit 150 receives a message to be transmitted to the controlling unit 160 from the slave device 200, the message transmission unit 153 may transmit the message which is converted by the message conversion unit 152 to the controlling unit 160.
If the message of the slave device 200 to respond to the request of the external network device 300 is input to the virtualization unit 150, the message transmission unit 153 may control the network communication unit 130 to transmit the message which is converted by the message conversion unit 152 to the external network device 300.
The IP address generation unit 154 may allocate an IP address to the slave device 200 if the slave device 200 is connected to the host device 100. Specifically, if the slave device 200 is connected to the host device 100, the IP address generation unit 154 may allocate an IP address for the slave device 200 connected to the host device 100 using an IP address for the host device 100. For example, if the IP address of the host device 100 is 127.0.0.1, the IP address generation unit 154 may allocate the IP address for the slave device 200 to be 127.0.0.1:0002. In this situation, the IP address generation unit 154 may generate an IP address for the slave device 200 connected to the host device 100 by searching for an available port of the host device 100.
The IP address generation unit 154 may store an IP address which is allocated to the slave device 200 in the storage unit 120. The IP address generation unit 154 may be implemented so that the same IP address is allocated to the slave device 200 which is repeatedly connected to the host device 100, or different IP addresses are allocated to the slave device 200 whenever the slave device is connected to the host device 100. The above operation of the IP address generation unit 154 may be performed when a user commands the virtualization for the slave device 200 or at the same time the slave device 200 is connected to the host device 100.
The controlling unit 160 may control the virtualized slave device 200 by applying the method of controlling the network device. In more detail, if the controlling unit 160 transmits a message to control the virtualized slave device 200, the controlling unit 160 may generate a message to comply with the communication protocol of the network device. The controlling unit 160 transmits the generated message complying with the communication protocol of the network device to the virtualization unit 150 and controls the virtualization unit 150 so that the message is converted to comply with the communication protocol of the slave device 200 and the converted message is transmitted to the slave device 200. If the host device 100 receives a response message from the slave device 200, the controlling unit 160 controls the virtualization unit 150 so that the message received through the local communication unit 140 is converted to comply with the communication protocol of the network device and thus the converted message is used to perform a service. Herein, the method of controlling the network device refers to a method of controlling a message between devices connected to a network, that is, the method of communicating between network devices using UPnP communication protocol.
If the message for the slave device 200 is received from the external network device 300 connected to the network, the controlling unit 160 may control the virtualization unit 150 to convert the message into a message which complies with the communication protocol of the slave device 200 and transmit the converted message to the slave device 200 since the received message complies with the communication protocol of the network device 300. If a response message is received from the slave device 200, the controlling unit 160 may control the virtualization unit 150 so that the message is converted to comply with the communication protocol of the network device 300 and thus the converted message is transmitted to the external network device 300.
As described above, since the host device 100 virtualizes the slave device 200 connected to the host device 100 as a network device and thus controls the slave device 200 in the network device controlling method, a developer may develop an application in consideration of only a single physical connection. In addition, since the slave device 200 connected to the host device 100 operates as a network device, the external network device 300 may easily control the slave device 200 connected to the host device 100.
The single slave device 200 is connected to the host device 100 in FIG. 1, but a plurality of slave devices may be connected to the host device 100 and a plurality of network devices may also be connected to the host device 100 via the network.
FIGS. 2 to 5 are views provided to explain a virtualization of a host device according to an exemplary embodiment.
FIG. 2 illustrates the connection relationship between the host device 100, the slave device 200, and the external network device 300 before the virtualization operation is performed. Specifically, the host device 100 is connected to a cradle 230, an accessory device 220 in a serial communication manner, and is connected to a specific device 260, a USB memory disk 210, a USB digital camera 240, and a USB camcorder (CAM) 250, for example, in a USB manner. The host device 100 is connected to an electric display 310, a printer 320, and a hand phone 330, for example, via a network. In this exemplary embodiment, the USB memory disk 210, the accessory device 220, the cradle 230, the USB digital camera 240, the USB CAM 250, and the specific device 260 are exemplary devices of the slave device 200, and the electric display 310, the printer 320, and the hand phone 330 are exemplary devices of the external network device 300.
FIG. 3 illustrates the connection relationship between the host device 100, the slave device 200, and the external network device 300 after the virtualization operation is performed for the slave device 200. Specifically, the physical connection relationship between the devices is identical to that of FIG. 2, but the slave devices 210 to 260 are virtualized as a network device having each an IP address. Specifically, the cradle 230 connected to the host device 100 in a serial communication manner is virtualized as a network device 360 having IP address ‘127.0.0.1:0003,’ and the USB cam 240 connected to the host device 100 in a USB manner is virtualized as a network device 380 having IP address ‘127.0.0.1:0005.’ The accessory device 220, the specific device 260, the USB memory disk 210, and the USB digital camera 240 may also be virtualized as a network device 350, 390, 340, and 370, respectively.
The slave device 200 is connected to the host device 100 in a serial communication manner and a USB manner in FIGS. 2 and 3, but the slave device 200 connected to the host device 100 via other local loops may also be virtualized.
FIG. 4 is a view provided to explain a controlling method of the host device 100 when a slave device is virtualized.
Referring to FIG. 4, a slave device 220 is physically connected to the host device 100 via a local loop, but if the slave device 220 is virtualized, the host device 100 may control a virtualized slave device 350 in a method of controlling a network device. In addition, since the slave device 220 is virtualized as a network device 350, the hand phone 330, which is an external network device, may easily control the virtualized slave device 350.
That is, the host device 100 and the external network device 300 connected each other via a network constitute a home network before the slave device 200 is virtualized as shown in FIG. 5, but the slave device 200 connected to the host device 100 is also an element which constitutes a home network after the slave device 200 is virtualized. Accordingly, the external network device 300 may easily control the slave device 200.
FIG. 6 is a flowchart of the process of controlling a slave device according to an exemplary embodiment.
Referring to FIG. 6, a slave device may be virtualized as a network device within network. Specifically, if the slave device is connected to a host device, an IP address is allocated to the slave device in operation 610, and the communication protocol of the slave device connected to the host device may be identified in operation 620. In more detail, if the slave device is connected to the host device, an IP address may be allocated to the slave device connected to the host device using an IP address of the host device. In this situation, an IP address for the slave device connected to the host device may be generated by searching for an available port of the host device. The type of slave device connected to the host device and the communication protocol of the slave device may be identified using a PnP communication protocol. An IP address allocated to the slave device, the type of the slave device, and the communication protocol of the slave device may be pre-stored, and may also be used in subsequent operations. The operation of allocating an IP address and the operation of identifying the communication protocol of the slave device may be performed in reverse order.
The virtualized slave device may be controlled in a method of controlling a network device. Specifically, a message of the host device and a message of the slave device are converted to comply with the communication protocol of the slave device and the communication protocol of the network device, respectively, according to the identified communication protocol of the slave device in operation 630. The converted messages are transmitted to the corresponding destinations in operation 640. For example, if the host device transmits a message indicating the command of controlling the virtualized slave device to comply with the communication protocol of the network device, the host device converts the message complying with the communication protocol of the network device into a message complying with the communication protocol of the slave device and transmits the converted message to the slave device. If the host device receives a response message from the slave device, the host device converts the response message into a message complying with the communication protocol of the network device since the message on the slave device complies with the communication protocol of the slave device, and the host device uses the converted message.
If the host device receives the message of the slave device from an external network device connected to the host device via a network, the host device converts the received message to comply with the communication protocol of the slave device since the received message complies with the communication protocol of the network device, and transmits the converted message to the slave device. If the host device receives a response message from the slave device, the host device converts the response message into a message which complies with the communication protocol of the network device and transmits the converted message to the external network device. The communication protocol of the network device may be implemented to be a UPnP communication protocol.
Alternatively, when the operation of converting the messages is performed, the message of the host device and the message of the slave device are analyzed and thus converted to correspond to the analyzed result. The alternative operation has been described above with reference to the message conversion unit 152, and thus detailed description will be omitted.
Accordingly, a developer may develop an application in consideration of only a single physical connection, and the slave device connected to the host device may easily be controlled from the outside as the slave device connected to the host device operates as a network device.
As described above, according to the method of controlling the slave device according to the exemplary embodiment, since the slave device connected to the host device is virtualized to be controlled, the slave device connected to the host device may be easily controlled using an external device, and a developer may develop an application in consideration of only a single physical connection. The method of controlling the slave device as shown in FIG. 6 may be applied not only to the host device which is configured as shown in FIG. 1 but also image reading devices having other structures.
Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

## Claims

1. A host device, comprising:
a network communication interface to connect the host device to a network device on a network;
a local communication interface to connect the host device to a slave device on a local network;
a virtualizer comprising at least one processor to virtualize the slave device as a virtual network device within the network by allocating an Internet Protocol (IP) address to the slave device;
a controller to control the slave device as the virtual network device; and
a storage to store the IP address of the slave device,
wherein the virtualizer allocates the IP address to the slave device by using a same IP address previously allocated to the slave device or by using a different IP address each time the slave device is connected to the host device.

2. The host device according to claim 1, wherein the virtualizer comprises:
a determiner to identify a communication protocol of the slave device;
a message converter to convert a message of the controller into a message which complies with the communication protocol of the slave device identified by the determiner, and to convert a message of the slave device into a message which complies with a communication protocol of the network device according to the communication protocol of the slave device identified by the determiner; and
a message transmitter to transmit the message converted by the message converter to a destination of the message.

3. The host device according to claim 2, wherein the message converter analyzes the message of the controller and the message of the slave device and performs a conversion according to a result of the analysis.

4. The host device according to claim 1, wherein the virtualizer further comprises:
an IP address generator to allocate the IP address to the slave device when the slave device is connected to the host device.

5. The host device according to claim 2, wherein
the message of the slave device is converted by the message converter into a message which complies with the communication protocol of the network device and the message transmitter transmits the converted message of the slave device to the network device, and
when a message of the network device is received by the controller in response to the converted message of the slave device being received by the network device, the controller controls the message converter to convert the message of the network device into a message which complies with the communication protocol of the slave device and controls the message transmitter to transmit the converted message of the network device to the slave device.

6. The host device according to claim 5, wherein the message transmitter controls the network communication interface to transmit the converted message of the slave device to the network device.

7. The host device according to claim 2, wherein the communication protocol of the network device is a universal plug-and-play (UPnP) communication protocol.

8. The host device according to claim 1, wherein the slave device is connected to the host device in at least one of a universal serial bus (USB) communication protocol, an IEEE 1394 communication protocol, a Serial Peripheral Interface (SPI) communication protocol, and a High-Definition Multimedia Interface (HDMI) communication protocol.

9. A method to control a slave device, the method comprising:
locally connecting the slave device to a host device on a first network;
virtualizing the slave device as a virtual network device within a second network by, allocating an Internet Protocol (IP) address to the slave device; and
controlling the slave device as the virtual network device,
wherein the virtualizing further comprises allocating the IP address to the slave device by using a same IP address previously allocated to the slave device or by using a different IP address each time the slave device is connected to the host device.

10. The method according to claim 9, wherein the virtualizing comprises:
allocating the IP address to the slave device when the slave device is connected to the host device; and
identifying a communication protocol of the slave device.

11. The method according to claim 10, wherein the controlling comprises:
converting a message of the host device into a message which complies with the communication protocol of the slave device;
converting a message of the slave device into a message which complies with a communication protocol of the network device, according to the communication protocol of the slave device;
transmitting the converted message of the host device to a destination of the message; and
transmitting the converted message of the slave device to a destination of the message.

12. The method according to claim 11, wherein
converting the message of the host device comprises analyzing the message of the host device and converting the message of the host device to correspond to a result of the analyzing of the message of the host device, and
converting the message of the slave device comprises analyzing the message of the slave device and converting the message of the slave device to correspond to a result of the analyzing of the message of the slave device.

13. The method according to claim 9, further comprising:
when a message of the another network device is received by the host device in response to a converted message of the slave device being received by the another network device, converting the message of the another network device into a message which complies with a communication protocol of the slave device and transmitting the converted message of the another network device to the slave device.

14. The method according to claim 13, further comprising:
converting the message of the slave device into a message which complies with a communication protocol of the another network device and transmitting the converted message of the slave device to the another network device.

15. The method according to claim 10, wherein the communication protocol of the network device is a universal plug-and-play (UPnP) communication protocol.

16. The method according to claim 9, wherein the slave device is connected to the host device in at least one of a universal serial bus (USB) communication protocol, an IEEE 1394 communication protocol, a Serial Peripheral Interface (SPI) communication protocol, and a High-Definition Multimedia Interface (HDMI) communication protocol.

17. A method to control a slave device, the method comprising:
locally connecting the slave device to a host device on a first network;
virtualizing the slave device as a virtual network device within a second network by allocating an Internet Protocol (IP) address to the slave device; and
converting, by the host device, a message from a first communication protocol to a second communication protocol to enable communication via the message between the slave device and another network device on the second network,
wherein the virtualizinq further comprises allocating the IP address to the slave device by using a same IP address previously allocated to the slave device or by using a different IP address each time the slave device is connected to the host device.

18. The method according to claim 17, wherein the first communication protocol is a communication protocol of the another network device and the second communication protocol is a communication protocol of the slave device, and the message is converted from the first communication protocol of the another network device into the second communication protocol of the slave device and transmitted to the slave device.

19. The method according to claim 17, wherein the first communication protocol is a communication protocol of the slave device and the second communication protocol is a communication protocol of the another network device, and the message is received by the host device from the slave device and converted from the first communication protocol of the slave device into the second communication protocol of the another network device.

20. The method according to claim 17, wherein the host device receives the message from the another network device, converts the message from a first communication protocol of the another network device into a second communication protocol of the slave device and transmits the converted message to the slave device.