Daisy chaining point-to-point link sensors

Embodiments of this present disclosure may include an industrial control system that uses a daisy chain communication network to couple point-to-point sensors (P2P sensors) for communication of data between respective P2P sensors and a controller. Each P2P sensor may couple to the daisy chain communication network via accessing circuitry. The accessing circuitry may include switching circuitry and flip-flop circuitry to control when each P2P sensors may communicate with the controller via the daisy chain communication network.

BACKGROUND

This disclosure relates generally to systems and methods for daisy chaining techniques within industrial automation systems. More particularly, embodiments of the present disclosure are directed toward daisy chaining of point-to-point link sensors of the industrial automation systems.

Industrial automation systems may include automation control and monitoring systems. The automation control and monitoring systems may monitor statuses and/or receive information from a wide range of devices, such as valves, electric motors, a wide range of sensors, other suitable monitoring devices, or the like. One or more components of the automation control and monitoring systems, such as programming terminals, automation controllers, input/output (I/O) modules, communication networks, human-machine interface (HMI) terminals, and the like, may use the statuses and/or received information to provide alerts to operators to change or adjust operation of one or more components of the industrial automation system (e.g., such as adjusting operation of one or more actuators), to manage the industrial automation system, or the like.

Generally, the networked devices described above may be associated with information, such as different statuses, sensing data, or the like. The information may relate to an operation of the industrial automation system and may be monitored by the automation control and monitoring systems. Certain communication systems are used to transmit the information to automation control and monitoring systems of the industrial automation systems. For example, each networked device may communicate with the automation control and monitoring systems via wired or wireless communication networks. With this in mind, it may be useful to improve methods for communication between automation control and monitoring systems and networked devices within industrial automation systems.

SUMMARY

In one embodiment, a system may include accessing circuitry that couples to a first point-to-point sensor of multiple point-to-point sensors. Each of the point-to-point sensors may couple to each other via respective intermediary accessing circuitry. The accessing circuitry may include flip-flop circuitry and switching circuitry. The system may include a controller coupled to the first point-to-point sensor via the accessing circuitry. The controller may transmit a first clock pulse to the accessing circuitry, where the flip-flop circuitry may reset in response to the accessing circuitry receiving the first clock pulse. The controller may transmit a second clock pulse to the accessing circuitry, where the flip-flop circuitry may set an output to a logic high signal in response to the accessing circuitry receiving the second clock pulse, and where the logic high signal may be used in coupling the first point-to-point sensors to a communication channel via the switching circuitry. The controller may also transmit or receive data via the communication channel during a time interval that corresponds to when the logic high signal is provided to the switching circuitry.

In another embodiment, a device may include switching circuitry for controlling communication between a first point-to-point sensor of a plurality of point-to-point sensors and a controller. The device may also include flip-flop circuitry that outputs a control signal in response to receiving a first combination of inputs. The switching circuitry may only communicatively couple the first point-to-point sensor to a communication channel shared with each of the plurality of point-to-point sensors and the controller in response to receiving the control signal.

In yet another embodiment, a tangible, non-transitory computer-readable medium may store instructions executable by a processor of an electronic device that, when executed by the processor, cause the processor to receive an indication of a request to communicate with a first point-to-point sensor of multiple point-to-point sensors. The point-to-point sensors may couple to each other in a daisy chain network, and each of the point-to-point sensors may communicatively couple to a communication channel via a respective accessing circuit of multiple accessing circuits. The tangible, non-transitory computer-readable medium may also store instructions executable by the processor of the electronic device that, when executed by the processor, cause the processor to transmit a number of clock pulses to a first accessing circuit of the accessing circuits that corresponds to the first point-to-point sensor. The number of clock pulses may include a first number of accessing circuits positioned in the daisy chain network between the controller and the first accessing circuit plus one. The tangible, non-transitory computer-readable medium may also store instructions executable by the processor of the electronic device that, when executed by the processor, cause the processor to communicate data between the first point-to-point sensor and the controller via the communication channel via the first accessing circuit after the number of clock pulses is transmitted to the first accessing circuit.

DETAILED DESCRIPTION

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. One or more specific embodiments of the present embodiments described herein will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

The present disclosure is generally directed towards systems and methods that enable communicating between point-to-point sensors (P2P sensors) via a daisy chain network. Sensors are generally components that are integral to industrial automation systems. For example, sensing data from a sensor may be leveraged in a diagnostic operation and/or a maintenance operation of a machine or other components of an industrial automation system. In particular, monitoring an operational state of a motor of the industrial automation system may use one or more sensor measurements. Being able to detect the status of temperature, humidity, vibration, and other operational parameters associated with the motor or other components of the industrial automation system may increase an effectiveness of diagnostic and/or maintenance operations, and may improve operation of the industrial automation system overall.

Within the industrial automation system, certain components and/or operation of certain components may benefit from different topologies of sensor networks. For example, rotating machinery operation may achieve relatively more benefit from a wireless sensing network topology than some wired sensing network topologies. Indeed, in a similar way, some components may benefit from P2P sensors communicating via a daisy chain network, where wireless networks may not be practical or feasible. As used herein, “daisy chain,” “daisy chained,” or “daisy chaining” may refer to a serial or generally sequential wiring of inputs to outputs of sequentially-arranged sensors. Using P2P sensors coupled in a daisy chain network may reduce an amount of wiring used to couple one or more sensors to the industrial control system, in addition to having other performance benefits.

A daisy chain network topology may not currently be a network topology option for certain sensors, such as P2P sensors. For example, P2P sensors may compete to communicate over a shared communication channel, and thus may interrupt communications of other P2P sensors if included in a daisy chain network. As such, in the presently disclosed embodiments, the P2P sensors may be leveraged as part of a bi-directional, digital, and wired network. The network may communicatively couple the P2P sensors and a master controller of the industrial control system via a shared communication channel, such as a network connection coupling the P2P sensors to the industrial control system. However, the shared communication channel may cause challenges when daisy chaining multiple P2P sensors.

When multiple P2P sensors are daisy chained, each of the P2P sensors may communicate through the shared communication channel. The communication from some P2P sensors may interrupt transmissions between the control system and the P2P sensors and/or may make communicating less efficient or effective. Thus, arbitrating access of the P2P sensors to the shared communication channel may improve communication technologies by enabling the P2P sensors to be coupled in a daisy chain network. As described herein, systems and methods that leverage accessing circuitry may be able to daisy chain multiple P2P sensors together. For example, this accessing circuitry (e.g., interconnected logic circuitry) may coordinate access of individual P2P sensors to the shared communication channel, thereby permitting communication between P2P sensors via a daisy chain network.

By using accessing circuitry to daisy chain P2P sensors, costs of implementing and maintaining an industrial control system may be reduced. For example, a star network topology and/or other one-to-one network topologies (e.g., 1:1 coupling) may have a relatively higher cost and/or a chance of maintenance issues due to the increased number of communicative couplings and the increased complexity of the communication network. Communicating between P2P sensors via a daisy chain network may provide a more efficient way to communicate with components of the industrial automation system. Additional benefits from using a daisy chain network topology of the sensors may include a decreased cost of deployment of a sensing system, a decreased complexity of a sensing system, and the like. These decreases in cost and/or complexity may improve efficiency of maintenance operations, improve profitability of operating or maintaining the industrial automation system, and the like.

An example accessing circuitry may include interconnected logic circuitry operable in response to various inputs and outputs, such as a clock signal and a selection signal, to coordinate accesses between the P2P sensors and the communication channel. For example, a master controller of the industrial control system may transmit a clock signal timed to select a P2P sensor. The interconnected logic circuitry may select the P2P sensor in response to the clock signal. After selection of the P2P sensor, the industrial control system may communicate with the P2P sensor until selecting a next P2P sensor. Coupling P2P sensors in this manner may enable any suitable number of P2P sensors to be daisy chained together within the industrial automation system. Additional details with regard to how the logic circuitry may use a clock signal to access one of a plurality of daisy chained P2P sensors will be discussed below with reference toFIGS. 1-5. These systems and methods described herein may also be combined with wireless communication networks to enable daisy chained P2P sensors to communicate wirelessly with the industrial control system, such as via a local networking device wirelessly communicating data between the industrial control system and the daisy chained P2P sensors.

By way of introduction,FIG. 1is a perspective view of an example industrial automation system10that may include daisy chained sensors, as described herein. The industrial automation system10may be controlled by an industrial control system11. In addition, the industrial automation system10may include stations having machine components and/or machines to conduct a particular function within an automated process, for example, an automated assembly line. The example automated process of the industrial automation system10may begin at a station12A used for loading objects, such as empty cans or bottles to be filled, into the industrial automation system10via a conveyor section14. The conveyor section14may transport the objects to a station12B to perform a first action, for example, washing the empty cans and/or bottles. As objects exit from the station12B, the conveyor section14may transport the objects to subsequent stations12to continue the manufacturing or assembly process. Clearly, for other applications, the particular system, machine components, machines, stations, and/or conveyors may be different or specially adapted to the application. In addition to the equipment described above, the industrial automation system10may also include motors, protection devices, switchgear, compressors, and the like.

One or more properties of components of the industrial automation system10may be monitored and controlled by an industrial control system11for regulating control variables. For example, sensing devices (e.g., sensors16) may monitor various properties of the industrial automation system10and generate outputs used during adjustments of the operation of the industrial automation system10. Scanners, gauges, valves, flow meters, and the like of the industrial automation system10may each generate sensing data used by the industrial control system11when determining adjustments to one or more operations of the industrial automation system10. These adjustments may be managed via control loops. For example, a control loop may include a controller of the industrial automation system10associated with a motor drive may receive data regarding a temperature of a connected motor and may adjust operations of the motor drive based on the data.

The industrial control system11may be communicatively coupled to a display/operator interface18(e.g., a HMI) and to one or more devices of the industrial automation system10. The industrial control system11may represent components of the industrial automation system10through visualizations of the components on the display/operator interface18. The industrial control system11may use data transmitted by sensors16to update visualizations of the components via changing one or more indications of current operations of the components. These sensors16may be any device adapted to provide information regarding process conditions. An operator22monitoring the industrial automation system10may reference the display/operator interface18to determine various statuses, states, and/or current operations or when adjusting operations of the industrial automation system10and/or for a particular component.

The industrial control system11may use networked devices24in managing operation of the industrial control system11. The networked devices24may be any suitable device within the industrial automation system10that communicates a status, a data packet, an alert, or the like, to the industrial control system11and/or to other networked devices24. The networked devices24may each include processing circuitry coupled to an example sensor16that enables transmission of sensing data to the industrial control system11.

The network of the industrial control system11may be a wired network, a wireless network, and/or a combination of the two. Based on the location of the sensors16, it may be desirable to couple two or more sensors16into a daisy chain communication network topology. That is, a collection of sensors16may be wired in electrical series with each other and transmit communication packets between each other via the created series circuit. Some sensors16, such as point-to-point sensors, may use additional components, for example, flip-flop circuitry and/or switching circuitry, when being daisy chained.

Leveraging a selection clock signal and interconnected logic circuitry may enable communication between point-to-point sensors via a daisy chain network. To help elaborate,FIG. 2is a block diagram of a first example communication network34of the industrial automation system10that includes accessing circuitry36(36A,36B). Each of the accessing circuitry36are coupled together in series as part of a daisy chain network. The accessing circuitry36may couple to a master controller38, for example, of the industrial control system11to each point-to-point sensors (P2P sensors)40(40A,40B) of the daisy chain network. The P2P sensors40are example sensors16that use additional components when communicating via a daisy chain network.

For example, each P2P sensor40may couple to the master controller38via logic circuitry and couplers disposed in respective accessing circuitry36. Each of the accessing circuitry36may include, for example, respective multi-pin couplers42(42A1,42A2,42A3,42B1,42B2,42B3) compatible with P2P sensors40, such as a M12-5 connector or other suitable field termination connector. By way of example, each multi-pin coupler42may operate using a particular number pins (e.g., five pins) including a subset of pins for daisy chaining the P2P sensors40and a subset of pins for communicating data between the P2P sensor40and the master controller38. The master controller38may transmit a selection signal pulse (SEL) via a first pin and may transmit a clock signal (CLK) via a second pin, where the first pin and the second pin may be the subset of pins for daisy chaining the P2P sensors40. The selection signal pulse and the clock signal may be used in combination with each other to select a particular P2P sensor40of the daisy chain network for communication, such as to retrieve sensing data. The master controller38may use a third pin and a fourth pin to supply power (e.g., L+ and L−) to the P2P sensor40. The master controller38may use a fifth pin to transmit a communication signal (C/Q Control) via a shared communication channel39used to transmit or receive data to or from the P2P sensor40(e.g., to communicate with the P2P sensor40). The third pin, fourth pin, and fifth pin may be the subset of pins for communicating data between the P2P sensor40and the master controller38. By coupling outputs from a multi-pin coupler42(e.g.,42A2) to adjacent multi-pin couplers42(e.g.,42B1), the P2P sensors40may considered to be daisy chained. To enable the master controller38to communication to any particular P2P sensor40, interconnecting couplings between flip-flop circuitry44(44A,44B) and switching circuitry46(46A,46B) may be used to help coordinate the communication protocol. It should be noted that the flip-flop circuitry44and/or the switching circuitry46may each be any suitable type of state-preserving device.

By way of example, if the master controller38were to establish a communication line with the first P2P sensor40A, the master controller38first may transmit a clock signal having a first clock pulse to the accessing circuitry36. The first clock pulse (and each subsequent clock pulse) may be received simultaneously by the flip-flop circuitry44of each accessing circuitry36. The first clock pulse resets the accessing circuitry36to prepare for selection of a P2P sensor40. To select the first P2P sensor40A, the master controller38may transmit a second clock pulse to the accessing circuitry36simultaneous with a selection signal pulse to the accessing circuitry36A. Propagation of the selection signal pulse is delayed through the accessing circuitry36by one clock cycle. In particular, the selection signal pulse may change the output of the flip-flop circuitry44A in response to the second clock pulse. When the output of the flip-flop circuitry44A changes (e.g., SEL′=1), the logical high selection signal is transmitted to both the flip-flop circuitry44B and to the switching circuitry46A, permitting access of the P2P sensor40A to the communication channel39of the daisy chain network. It is noted that the master controller38uses 2 clock pulses (e.g., n+1) to select the first P2P sensor40A corresponding to n=1.

The master controller38may use three clock pulses to select the second P2P sensor40A. For example, before the third clock pulse is received by the flip-flop circuitry44, the selection signal input to the flip-flop circuitry44A returns to a logical low signal (e.g., SEL=0) to complete transmission of the selection signal pulse input. When the flip-flop circuitry44receive the third clock pulse, the flip-flop circuitry44A changes output in response to the logical low signal of the selection signal input to output a logical low signal. However, since the selection signal pulse is delayed behind the clock pulses, the flip-flop circuitry44B changes its output in response to the previous selection signal pulse (SEL′=1) input from the flip-flop circuitry44A circuitry after the second clock pulse. The flip-flop circuitry44B may change from outputting a logical low signal to outputting a logical high signal of the selection signal pulse, thereby permitting access of the P2P sensor40B to the communication channel39of the daisy chain network. The activation of the accessing circuitry36B happens at the same time that the deactivation of the accessing circuitry36A, thus restricting access of the P2P sensor40A to the communication channel while the P2P sensor40B is actively accessing the communication channel.

To elaborate further on how the first example communication network34operates,FIG. 3is a flowchart of a method58for enabling communication between the P2P sensors40and the industrial control system11via the communication network34. For ease of explanation,FIG. 3is explained using components ofFIG. 2. The method58may be performed by the master controller38to select a respective of the P2P sensors40, such as during sensing, to retrieve sensing data, or the like. Although the method58is described below as being performed by the master controller38, it should be understood that any suitable control device, such as the industrial control system11, may perform the method58. Moreover, although the following description of the method58is described in a particular order, it should be understood that the method58may be performed in any suitable order.

At block60, the master controller38may receive an indication of a request to communicate with a sensor node (n). Each sensor node may be a different P2P sensor40. For ease of description, the method58is described in terms of accessing circuitry36A and with a target sensor node of the P2P sensor40A. The master controller38may receive the indication in response to the industrial control system11transmitting commands as part of a sensing operation to initiate communication with the P2P sensor40A.

At block62, the master controller38may transmit n+1 clock pulses (e.g., high-to-low, falling edge, low-to-high, rising edge). The n+1 clock pulses correspond to one more than a numerical position of the P2P sensor40relative to the master controller38. For example, a second position sensor node corresponding to P2P sensor40B may receive three clock pulses from the master controller38when the second P2P sensor40B is to be selected. The master controller38may generate a clock signal having a count of clock pulses equal to one greater than a number corresponding to the sequential position of the P2P sensor40A, or one greater than the indication of the sensor node (n) to be enabled. In this example, the P2P sensor40A is the first sensor sequentially coupled to the master controller38, and thus is to be transmitted a clock signal having two clock pulses (e.g., two rising edges). However, if the master controller38were to select the third sequentially coupled P2P sensor40C (not pictured but presumed as sequentially coupled to P2P sensor40B), the master controller38may transmit a clock signal having four clock pulses.

Referring back to the example of communicating with the second P2P sensor40C, the first clock signal transition may reset a state of the flip-flop circuitry44A and the second clock signal transition, when paired with a logical high selection signal, may set a state of the flip-flop circuitry44A of the accessing circuitry36A to output a logical high signal.

To communicate with sensor node (n), at block64, the master controller38may transmit a selection signal pulse to multi-pin coupler42A1. The selection signal pulse may be timed such that the targeted flip-flop circuitry44receives a rising clock signal transition at an at least partially overlapping time as when the targeted flip-flop circuitry44receives a logical high selection signal pulse. A period of time after the master controller38transmits a logical high selection signal, the master controller38transmits a logical low selection signal to form a selection signal pulse. The selection signal pulse may permit the P2P sensor40A to access the communication channel to the master controller38, when transmitted during a time period that overlaps with the clock signal transmission. When the selection signal pulse is received at the flip-flop circuitry44at the same time as a clock pulse of the clock signal, the selection signal pulse is clocked through the flip-flop circuitry44A to close the switching circuitry46A. This may be permitted due to the state operation of the flop-flop circuitry44A. For example, if the flip-flop circuitry44A included a delay-type flip-flop (e.g., D flip-flop), the following state table, Table 1, may show the expected outputs:

Having the outputs of the flip-flop circuitry44A follow behavior of the D-type flip-flop enables the selection signal pulse to propagate through accessing circuitry36. For example, when both the clock signal input to the flip-flop circuitry44A and the selection signal pulse to the flip-flop circuitry44A are transitioned to logical high signals, the selection signal pulse output from the flip-flop circuitry44A is set to output a logical high signal. But, the selection signal pulse output from the flip-flop circuitry44A is reset to a logical low signal when the clock signal transitions from a logical low signal to a logical high signal and the selection signal pulse is a logical high signal. This transition pattern causes the state of flip-flop circuitry44A to reset to a logical low signal and thus output a logical low selection signal pulse output.

When the selection signal pulse and the clock signal overlap, the switching circuitry46A may receive the high selection signal pulse output signal from the flip-flop circuitry44A. The switching circuitry46A may close in response to the high selection signal pulse signal and permit communication signals (C/Q Control) to transmit to the multi-pin coupler42A3. The multi-pin coupler42A2may also receive the selection signal for transmission to the multi-pin coupler42B1as a selection signal pulse.

In response to the multi-pin coupler42A3receiving the communication signal (C/Q Control), the P2P sensor40A may communicate with the master controller38. Thus, at block66, the master controller38may transmit and/or receive data to/from the sensor node (n) (e.g., selected sensor node). For example, the P2P sensor40B may send sensor data back to the master controller38via a path including the multi-pin coupler42B3, multi-pin coupler42B1, the multi-pin coupler42A2, and multi-pin coupler42A1. It is noted that if the master controller38selected the P2P sensor40B instead of the P2P sensor40A, the P2P sensor40B may transmit sensing data to the master controller38without interruption from the P2P sensor40A. In this way, the P2P sensors40are successfully daisy chained to the master controller38.

In some embodiments, the P2P sensor40A has two operational modes Input-Output (IO) Mode and IO Link Mode. While the P2P sensor40A is in the IO mode, the P2P sensor40A is isolated from the communication network34and unselected. Applying the communication signal (C/Q Control) for a threshold duration of time that corresponds to a time required to wake up or reconnect the P2P sensor40A to the communication network34may operate the P2P sensor40A into the IO Link Mode from the IO Mode. For example, a current load for about 70-90 micro-Siemens (μS) of 0.4-0.6 Amperes (A) (e.g., 0.5 A for 80 μS) may enable the P2P sensor40A to operate into the IO Link Mode for sensing data transmission to the master controller38. A switch, such as a transistor and/or an analog switch, rated for 0.5 A with relatively low resistance capable of maintaining a margin in a switching voltage thresholds may be included in the switching circuitry46A to permit operational switching of the P2P sensor40A.

FIG. 2andFIG. 3both describe multi-pin couplers42that use two pins for providing the daisy chain topology. In some embodiments, one pin (instead of two pins) may be available for daisy chaining the P2P sensors40, where remaining pins may be used for communicating via the daisy chain network or in other suitable operations. By including additional logic circuitry, the circuitry ofFIG. 2may be modified to accommodate a daisy chain topology that uses one pin instead of two pins of the multi-pin couplers42.

To help elaborate,FIG. 4is a block diagram of a second example communication network34of the industrial automation system10that includes accessing circuitry36(36D,36E). Each of the accessing circuitry36are coupled together via the shared communication channel to provide the daisy chain communication network.

The communication network34includes additional flip-flop circuitry44, watchdog timers47(47A,47B), and logic gates48(48A,48B). These components couple between multi-pin couplers42(42A1,42A2,42A3,42B1,42B2,42B3) and the P2P sensors40. In general, the communication network34leverages consecutive clock signal transitions and the watchdog timers47to daisy chain the P2P sensors40.

If the master controller38were to select the P2P sensor40A, the basic operation of first example communication network34ofFIG. 2may apply. In this way, the master controller38may select the P2P sensor40A using selectively transmitted clock pulses to activate or deactivate the accessing circuitry36over time. For example, for the master controller38to activate the P2P sensor40A, the master controller38may transmit a first clock pulse to reset the accessing circuitry36and start a timing window of watchdog timers47. During the timing window, the accessing circuitry36permits the master controller38to select a P2P sensor40A. While the timing window is active, the master controller38may transmit a second clock pulse to flip-flop circuitry44A to the flip-flop circuitry44A, while the flip-flop circuitry44A also receives the logical high signal output from the watchdog timer47A associated with the timing window. This logical high signal output from the watchdog timer47A at the rising clock pulse may cause the change in the output from the flip-flop circuitry44A. In addition, the second clock pulse may also cause the flip-flop circuitry44B to change an output from the inverted output pin. The output may change from a logical low signal to a logical high signal in response to the second clock pulse. The logic gate48A may then permit the simultaneous logical high signals to close the switching circuitry46A, thereby permitting the P2P sensor40A to access the communication channel coupled to the master controller38.

In a similar way, if the master controller38were to select the second P2P sensor40B, the master controller38may transmit a third clock pulse to the flip-flop circuitry44. The third clock pulse may cause the flip-flop circuitry44C to change its inverted output to a logical low signal, disabling the accessing circuitry36D. The third clock pulse may also cause the flip-flop circuitry44B to change its output to a logical high signal, similar to the flip-flop circuitry44A in response to the second clock pulse. Thus, the third clock pulse may activate the accessing circuitry36E to permit the P2P sensor40B to access the communication channel and the master controller38. To deactivate the accessing circuitry36E, the master controller38may transmit a fourth clock pulse. The fourth clock pulse may also activate the next sequentially coupled P2P sensor40).

To elaborate on how the second example communication network34operates,FIG. 5is a flowchart of a method90for enabling communication between the P2P sensors40and the industrial control system11via the communication network34. For ease of explanation,FIG. 5is explained using components ofFIG. 4. The method90may be performed by the master controller38to select a respective one of the P2P sensors40for communication of sensing data and/or for ongoing sensing operations. Although the method90is described below as being performed by the master controller38, it should be understood that any suitable control device, such as the industrial control system11, may perform the method90. Moreover, although the following description of the method90is described in a particular order, it should be understood that the method90may be performed in any suitable order.

At block92, the master controller38may receive an indication of a request to communicate with a sensor node (n). Operations performed at block92are the same or substantially similar to operations of block60, and thus are relied upon herein.

In response to receiving the indication of the request, at block94, the master controller38may determine whether a timeout (TO) interval has passed. The TO interval corresponds to a timing window that is initiated in response to a first clock signal (CLK) transition received by the watchdog timers47. In some embodiments, sensor node selection operations may not overlap and, in this way, the master controller38may wait until the TO interval has passed.

When the TO interval has passed, at block96, the master controller38may transmit a first clock pulse. The first clock pulse is used to activate the watchdog timers47. For ease of description, the watchdog timers47are described herein as activating in response to a rising clock signal edge (e.g., logical low to logical high). However, it should be understood that any suitable combination of logic circuitry may be used to implement these techniques, such that a falling edge may activate the watchdog timers47. When the watchdog timers47receive the first clock pulse, a new TO interval begins. The TO interval corresponds to a duration of time that a logical high signal transmits as an input to the flip-flop circuitry44from the watchdog timers47. Each watchdog timer47outputs a logical high signal to each flip-flop circuitry44generally synchronous or at least partially at a same time. In this way, the flip-flop circuitry44D receives the logical high signal from the watchdog timer47B at a same time, or at a substantially similar time, as the flip-flop circuitry44A receives the logical high signal from the watchdog timer47A. The watchdog timers47may manage a TO interval during which any of the point-to-point sensors may be selected for communication with the controller. When the TO interval begins, the master controller38has until the end of the TO interval to select a sensor node and to communicate with the sensor node, such as to receive sensing data from one of the P2P sensors40.

To communicate with the sensor node (n), at block98, the master controller38may transmit a clock having n clock pulses to multi-pin coupler42A1. The first clock pulse may disable each P2P sensor40and may initiate the watchdog timers47(e.g., block96). Subsequent clock pulses may enable the signal output from the watchdog timers47to be clocked through the flip-flop circuitry44. The flip-flop circuitry44may operate according to particular rules based on a type of flip-flop circuitry used. For example, when the flip-flop circuitry44includes D-type flip-flops, the flip-flop circuitry44may behave according to rules of Table 1. Different flip-flop types may be used with the embodiments described herein and may include additional or alternative circuitry to support its operation. In this way, each adjacent clock pulse may be used as a selection signal to enable communication between the selected P2P sensor40and the master controller38. The switching circuitry46may receive a logical high signal resulting from the interconnected flip-flop circuitry44and may close in response to receiving the logical high signal. The switching circuitry closing may permit communication between the master controller38and the P2P sensor40. It is noted that the logic gates48are depicted as AND gates, however any suitable logic gate may be used to drive selection circuitry to operate as described, including suitable combinations of AND gates, NAND gates, OR gates, NOR gates, XOR gates, inverting gates, or the like.

Generally, the second clock pulse (e.g., sequential to the first clock pulse of block96) begins communication between the master controller38and the P2P sensor40A. This may cause the output of the first watchdog timer47A to transmit from the flip-flop circuitry44A to the flip-flop circuitry44B. If a third clock pulse were included with the clock signal, the first sensor node may disable in response to the third clock pulse and pass the clock signal onto the second sensor node corresponding to P2P sensor40B. This may set the flip-flop circuitry44B, resulting in the output of a logical high signal. While each subsequent sensor node is enabled, the master controller38may communicate with the P2P sensor40using the communication signal (C/Q Control).

At block100, the master controller38may communicate with the sensor node (n) via the communication signal (C/Q Control). Data transmission between the P2P sensor40and the master controller38may continue until the watchdog timer47expires or until the communication signal (C/Q Control) is disabled. When either of those signals transitions to logical low, communication stops between the master controller38and the selected P2P sensor40.

For example, if the master controller38were to receive an indication selecting P2P sensor40B, the master controller38may wait for a current selection operation to end. When the TO interval ends, the master controller38may transmit a first clock pulse to each watchdog timer47via the clock signal to start a new TO interval and/or to disable each sensor node. While the new TO interval is ongoing, the master controller38may transmit two additional, sequential clock pulses to select the n=2 P2P sensor40B. While the P2P sensor40B is selected, the master controller38may communicate with the P2P sensor40B without interruption by data from the P2P sensor40A or from other P2P sensors40. The master controller38may continue communication with the P2P sensor40B until the TO interval ends or until the master controller38ends communication itself.

In each of these described examples, the master controller38may be replaced or provided in conjunction with wireless gateway circuitry to wirelessly communicate with the industrial control system11. For these cases, the wireless gateway circuitry may include transceiver circuitry, transmitting circuitry, receiving circuitry, or the like. Any suitable type of wireless communication may be performed in combination with at least some of the techniques described above. In addition, certain encryption techniques may be used to secure data transmitted between the wireless gateway circuitry and the industrial control system11.

Thus, technical effects of the present disclosure include techniques for coupling point-to-point sensors in a daisy chain network topology. In this way, a two or more point-to-point sensors may be sequentially coupled together (e.g., daisy chained) and able to communicate with a master controller of an industrial control system without interference from other point-to-point sensors coupled in the daisy chain network. In this way, a point-to-point sensor may perform sensing operations, or otherwise generate information, to be transmitted to the industrial control system. In response at least to the master controller using a selection clock signal to select the point-to-point sensor, the point-to-point sensor and the master controller may communicate freely while the point-to-point sensor is selected. In some industrial automation systems, it may be advantageous to daisy chain sensors together. For example, communicating between point-to-point sensors via a daisy chain network may reduce maintenance costs and/or may reduce installation costs. By including additional circuitry and leveraging the selection clock signal, the master controller may selectively communicate with point-to-point sensors.