JP5099334B2 - PLC slave - Google Patents

Description

  The present invention relates to a remote input / output terminal (hereinafter referred to as a slave) that is connected to a programmable controller (hereinafter referred to as a PLC) through communication and functions as an input / output terminal. The present invention relates to a PLC slave to which a photoelectric sensor is connected.

  A sensing system in which a plurality of transmissive photoelectric sensors are connected to a PLC via a slave is conventionally known. An example of such a sensing system is shown in FIG.

  As shown in the figure, this sensing system is configured by connecting one PLC 1 and N slaves 2-1, 2-2,...

  In this example, a building block type is adopted as the PLC 1. In the illustrated example, the PLC 1 connects the power supply unit 11, the CPU unit 12, the communication master unit 13, and the two I / O units 14 and 14 on a backplane on which a system bus (not shown) is laid. The power supply unit 11 supplies power to the units 12 to 14 via a power supply line on the system bus.

  The CPU unit 12 performs overall control of the entire PLC 1, and although not shown in the figure, a user memory for storing a user program, an input / output memory for storing input / output data, and the like An ASIC incorporating a user program execution function, a microprocessor for overall control of the entire unit, a system memory for storing a system program to be executed by the microprocessor, and a microprocessor for executing various programs A work memory used as a work area is provided.

  The microprocessor executes the system program stored in the system memory. When the operation mode is the RUN mode, the microprocessor performs the input / output update process, the user program execution process, and the peripheral service process as one cycle. It is structured to repeat the process.

  Here, as is well known to those skilled in the art, the input / output update process is an input update process in which input data captured from the input / output unit 14 and the communication master unit 13 is written to the input area of the input / output memory. , And output update processing for sending output data read from the output area of the input / output memory to the input / output unit 14 and the communication master unit 13.

  User program execution processing sequentially reads out each instruction word constituting the user program from the user memory, executes it referring to the input / output data stored in the input / output memory, and uses the execution result as the input / output memory. It consists of a series of processes that rewrite the contents of.

  The peripheral service process includes a process of exchanging data with a tool device (not shown) or exchanging data via communication with another PLC via a network.

  Although not shown, the communication master unit 13 includes a communication processing unit for exchanging input / output data with each of the slaves 2-1, 2-2,. , A transfer intermediary memory (generally composed of a dual port memory) for exchanging data with the CPU unit 11 by handshake processing via the system bus on the backplane, and overall control of the entire unit It is comprised including the microprocessor for.

  In the output update process described above, the output data to be transmitted to any of the slaves 2-1, 2-2,... It is written by control on the 12 side. The output data stored in the predetermined area of the transfer intermediation memory in this way is read from the predetermined area of the transfer intermediation memory at any time or at a predetermined timing, and by the communication via the network 3, the slaves 2-1, 2-2,. · · Sent to the appropriate 2-N.

  On the other hand, the input data received from any of the slaves 2-1, 2-2,..., 2-N by communication via the network 3 is written in a predetermined area of the transfer mediating memory. The input data written in the predetermined area of the transfer mediating memory in this manner is read by the control on the CPU unit 12 side and written in the input area of the input / output memory in the CPU unit 12 in the input update process described above.

  In this way, in the input / output update process, the input / output data is exchanged between the CPU unit 12 and the communication master unit 13 via the transfer mediation memory, and the communication master unit is obtained at any time or at a predetermined timing. 13 and each of the slaves 2-1, 2-2,..., 2-N exchange input / output data via communication via the network 3.

  A functional configuration diagram of a conventional slave is shown in FIG. 13, and a hardware block diagram is shown in FIG. Each of the slaves 2-1, 2-2,..., 2-N includes an output terminal block OUT (see FIG. 12), an input terminal block IN (see FIG. 12), and an input processing unit 21 (see FIG. 13). And an output processing unit 22 (see FIG. 13) and a communication processing unit 25 (see FIG. 13).

  The output terminal block OUT indicates the amount of light emitted from each of the light projectors ST (1) to (M) of a plurality of (in this example, M) transmissive photoelectric sensors in a high light intensity state (in this example, 100% light emission amount). State) and a low light emission amount state (in this example, 50% light emission state), a plurality of (in this example, M) output terminals to be connected to each of the light emission amount switching control terminals Is included. The input terminal block IN is one or more inputs to be connected to each of the sensor output terminals of the light receivers SR (1) to (N) of a plurality (M in this example) of transmissive photoelectric sensors. Includes terminals.

  The input processing unit 21 takes in an input signal input from the outside to the input terminals constituting the input terminal block IN and generates corresponding input data. The output processing unit 22 generates an output signal based on the given output data, and sends it out from the corresponding output terminal of the output terminal block OUT. The communication processing unit 25 exchanges input / output data with the communication master unit 13 of the PLC 1 via the network 3.

  More specifically, as shown in FIG. 14, the function of the input processing unit 21 is realized by, for example, an input circuit 210 for performing electrical conversion with an external input, and the output processing unit described above. 22 functions are realized by the output circuit 220 for performing electrical conversion with the external output, and further, the functions of the communication processing unit 25 are realized by, for example, the communication MPU 251, the communication ASIC 252, and the transceiver 253. .

  FIG. 15 shows an explanatory diagram of workpiece detection by the transmission photoelectric sensor. In FIG. 2A, CV is a conveyor, W is a workpiece, ST is a light projector of a photoelectric sensor, and SR is a light receiver of the photoelectric sensor. In this example, a projector ST and a light receiver SR are arranged opposite to each other across a conveyor CV that conveys a workpiece W. The projection from the projector ST (sensor projection) is in a continuous projection state (ON).

  When the work W transported by the conveyor CV blocks the optical path connecting the projector ST and the light receiver SR (with a work), the light receiving state of the light receiver SR (sensor light reception) is “no light reception”. Output (sensor output) is “ON”, and the output from the slave 2 to the PLC 1 (slave output) is also “ON”. On the other hand, when the workpiece W conveyed by the conveyor CV does not block the optical path connecting the projector ST and the light receiver SR (no workpiece), the light reception state (sensor light reception) of the light receiver SR is “light reception”. The output (sensor output) of the light receiver SR is “OFF”, and the output (slave output) from the slave 2 to the PLC 1 is also “OFF”. Therefore, on the PLC 1 side, as long as the photoelectric sensor is normal, it can be recognized that “work is present” if the slave output is “ON”, and “no work” if it is “OFF”.

  As is well known to those skilled in the art, in this type of transmissive photoelectric sensor, the optical axis misalignment between the projector and the light receiver, dirt on the lens, deterioration of the LED used for the light emitting element, etc. As a result, a so-called “sensor abnormality” may occur.

  Conventionally, in order to prevent such sensor abnormality from occurring, an operator manually performs optical axis adjustment, lens cleaning, LED deterioration diagnosis, and the like while the operation target equipment is in a stopped state. It was customary. However, since such countermeasures depend on the hands of workers, there is a problem that a sufficient effect cannot be expected as the number of photoelectric sensors increases.

  As a solution to such a problem, a method for diagnosing abnormality of a transmissive photoelectric sensor using a light quantity switching function is known (see, for example, Patent Document 1). In order to carry out this method, a projector having a projection light quantity switching control terminal is used. In such a projector, the signal to be supplied to the projection light amount switching control terminal is switched between the first logical value and the second logical value, so that the projection light amount is 100% and 50%. It is possible to switch to the amount of light emitted. Further, for this method, it is necessary to incorporate the light quantity batch switching program shown in FIG. 17 and the sensor abnormality detection output program shown in FIG. 18 as user programs on the PLC side.

FIG. 16 is an explanatory diagram of an abnormality diagnosis method for a transmissive photoelectric sensor using a light quantity switching function. In this method, by manually turning on / off the light amount switch provided on each slave in a maintenance mode in which no work flows (no work), all the projectors connected to that slave are projected. The amount of light is changed in a lump such as 100% projected light amount state → 50% projected light amount state → 100% projected light amount state (see the ladder diagram of FIG. 17). Then, as shown in FIG. 16A, when the target sensor is normal, the sensor output does not change from OFF to OFF to OFF before and after the light amount change, whereas FIG. As shown in b), if the target sensor has a sensor abnormality (optical axis misalignment between the projector and receiver, lens contamination, LED degradation, etc.), before and after the light quantity change, Since the sensor output changes from OFF to ON to OFF, the PLC captures the sensor output obtained in this way, and the abnormality detection output program (see the ladder diagram in FIG. 18) is executed, so that abnormality detection is performed for that sensor. Output is emitted.
OMRON “Sensing Component Catalog 2008”, page 224

  However, in the sensor abnormality diagnosis method in which the above-described light quantity batch switching program (see the ladder diagram in FIG. 17) and the sensor abnormality detection output program (see the ladder diagram in FIG. 18) are incorporated as a PLC user program. As the number of photoelectric sensors increases, the capacity of the user program on the PLC side increases, the contents of the program become complicated, and the cycle time of the PLC increases, adversely affecting the tact time of the system. Since the inspection is performed by switching the amount of light emitted from the slave via the switch, the switching time is delayed by the cycle time of the PLC or the communication cycle of the network, which makes it difficult to detect abnormality of the photoelectric sensor in real time.

  The present invention has been made paying attention to such conventional problems, and the object of the present invention is in a sensing system in which a plurality of transmission type photoelectric sensors are connected to a PLC via a slave. An object of the present invention is to provide a PLC slave capable of reducing the burden of a user program on the PLC side and capable of detecting an abnormality of a photoelectric sensor in real time, for implementing a sensor abnormality diagnosis method using projected light quantity switching.

  Another object of the present invention is that the above-described real-time photoelectric sensor abnormality detection is performed not only in the maintenance mode in which the operation of the control target equipment is stopped and the flow of the work is stopped, but also in the operation of the control target equipment. Even so, it is to provide a PLC slave that can be implemented at any time.

  Another object of the present invention is to provide a PLC slave capable of diagnosing a sensor abnormality while detecting a workpiece.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description of the specification.

  It is considered that the above technical problem can be solved by a PLC slave having the following configuration.

  That is, the PLC slave includes a communication processing unit, an output terminal block, an input terminal block, an output processing unit, an input processing unit, and a control unit.

  The communication processing unit exchanges input / output data with the PLC via the network. The output terminal block should be connected to each of the projection light quantity switching control terminals for switching the projection light quantity of each projector of one or more transmissive photoelectric sensors between a high projection light quantity state and a low projection light quantity state. One or more output terminals are included. The input terminal block includes one or more input terminals to be connected to each of the light receiving output terminals of each light receiver of the one or more transmissive photoelectric sensors. The output processing unit generates an output signal based on the given output data and sends it out from the corresponding output terminal of the output terminal block. The input processing unit takes in an input signal input from the outside to an input terminal constituting the input terminal block and generates corresponding input data. The control unit includes a sensor abnormality diagnosis means and a sensor abnormality detection contact memory.

  The sensor abnormality diagnosing means outputs the projection light quantity at least once between the high light quantity light quantity state and the low light quantity light quantity state in each light projector of one or more transmissive photoelectric sensors. Input from the input processing unit so that the sensor output corresponding to each of the high light projection amount state and the low light emission amount state is read from each of the light receivers paired with each projector. Controls the data capture, and when the sensor output captured in the high light output state is receiving light, each transmission type photoelectric is determined based on whether the sensor output captured in the low light output state receives light or does not receive light. Diagnose whether the sensor is abnormal.

  The sensor abnormality detection contact memory includes a sensor abnormality detection contact memory that stores data corresponding to a diagnosis result by the sensor abnormality diagnosis means as an operation state of the abnormality detection contact of each corresponding transmission type photoelectric sensor.

  According to such a configuration, the PLC side simply refers to the contents of the sensor abnormality detection contact memory without giving an instruction for sensor abnormality diagnosis by switching the amount of light to be projected to the slave side. Since the operation state of the sensor abnormality detection contact of each corresponding transmissive photoelectric sensor can be acquired, in a sensing system in which a plurality of transmissive photoelectric sensors are connected to a PLC via a slave, a sensor that uses projected light amount switching Regarding the implementation of the abnormality diagnosis method, it is possible to reduce the burden on the user program on the PLC side and to detect abnormality of the photoelectric sensor in real time.

  In a preferred embodiment, the sensor abnormality diagnosing means included in the control unit constantly switches between a high light projection amount state and a low light emission amount state in each of the light projectors of the one or more transmissive photoelectric sensors. Repeatedly controls the output data output to the output processing unit, and captures input data from the input processing unit so that the sensor output corresponding to each of the high light projection amount state and the low light emission amount state is repeatedly read. When the sensor output captured in the high light output state is receiving light, and when the sensor output captured in the low light output state is determined not to receive light, the The transmission type sensor diagnoses that the sensor is abnormal.

  According to such a configuration, since sensor abnormality can be regularly diagnosed, the above-described real-time photoelectric sensor abnormality detection is performed not only in the maintenance mode in which the control target equipment is stopped and the work flow is stopped, but also in control. Even when the target equipment is in operation, it can be carried out regularly.

  In a preferred embodiment, the control unit includes data corresponding to a determination result as to whether or not the sensor output that is captured in the high light projection amount state is “no light reception” in the sensor abnormality diagnosis unit, A work detection contact memory is further included for storing the operation state of the work detection contact of each corresponding transmission type photoelectric sensor.

  According to such a configuration, on the PLC side, the operation state of the work detection contact of each corresponding transmission type photoelectric sensor is constantly acquired, and in addition, the sensor of each corresponding transmission type photoelectric sensor is obtained. Since the operation state of the abnormality detection contact can be acquired, it is possible to diagnose a sensor abnormality while detecting a workpiece.

  The sensor abnormality diagnosis means may automatically operate immediately after the slave is turned on. According to such a configuration, it is possible to diagnose a sensor abnormality using a period in which there is no work immediately after the operation of the control target facility.

  According to the present invention, in a sensing system in which a plurality of transmissive photoelectric sensors are connected to a PLC via a slave, a sensor abnormality diagnosis method using projected light quantity switching is implemented. In addition to reducing the burden, it is possible to detect abnormality of the photoelectric sensor in real time.

  A preferred embodiment of a PLC slave according to the present invention will be described below in detail with reference to the accompanying drawings.

  The configuration of the slaves 2-1, 2-2, ... 2-N of the present invention will be described in detail. A functional configuration diagram of the slave of the present invention is shown in FIG. 1, and a hardware configuration diagram is shown in FIG.

  As is apparent with reference to FIGS. 1, 2, and 12, each of the N slaves 2-1, 2-2,..., 2-N includes a communication processing unit 25 and an output terminal block OUT. , An input terminal block IN, an output processing unit 22, an input processing unit 21, and a control unit 24.

  The communication processing unit 25 exchanges input / output data with the PLC 1 (more precisely, the communication master unit 13) shown in FIG.

  The output terminal block OUT is configured to reduce the amount of light emitted from each of the projectors ST (1) to (M) of one or more transmissive photoelectric sensors to a high light amount state (in this example, a 100% light amount state). One or two or more output terminals OUT (1) to (M) to be connected to each of the projection light quantity switching control terminals for switching to the projection light quantity state (in this example, the 50% projection light quantity state). Contains.

  The input terminal block IN is 1 or 2 to be connected to each of the light receiving output terminals SR (1) to (M) of the light receivers SR (1) to (M) of one or more transmissive photoelectric sensors. The above input terminals IN (1) to (M) are included.

  The output processing unit 22 generates an output signal based on the given output data, and sends it out from the corresponding output terminals OUT (1) to (M) of the output terminal block OUT. The input processing unit 21 captures input signals input from the outside to the input terminals IN (1) to (M) constituting the input terminal block IN and generates corresponding input data.

  As shown in FIG. 1, the control unit 24 includes various programs 24-2 functioning as sensor abnormality diagnosis means, various parameters 24-1, which will be described later, work detection contacts 24a, which will be described later, and photoelectrics, which will be described later. The sensor abnormality detection contact 24b is included.

  More specifically, the functions of the input processing unit 21 and the output processing unit 22 shown in FIG. 1 are as follows. As shown in FIG. 2, the input circuit 210 that performs electrical conversion with an external input, This can be realized by the output circuit 220 that performs the target conversion. Further, as shown in FIG. 2, the function of the communication processing unit 25 shown in FIG. 1 is a communication ASIC 252 that controls the transceiver 253 in response to a command from the communication MPU 251 that supervises the entire communication process and the communication MPU 251. , A transceiver 253 constituting the communication physical layer, and a dual port RAM (DP-RAM) 254 that mediates the exchange of data between the communication MPU 251 and the control MPU 241.

  Further, the functions of the control unit 24 shown in FIG. 1 are referred to when executing a program, a control MPU 241 that performs overall control of the operation of the slave, a program storage memory 242 that stores a program to be executed by the control MPU 241. The parameter storage memory 243 for storing various parameters and the work memory 244 used as a work area when the control MPU 241 executes various programs can be used.

  Here, the program storage memory 242 stores various programs 24-2 (see FIGS. 3 to 5) constituting the sensor abnormality diagnosis means. The parameter storage memory 243 stores parameters T (ms) and t (ms), which will be described in detail later.

  Further, in the work detection contact area 244a of the work memory 244, the work detection contact 24a of each corresponding transmission type photoelectric sensor 2-1, 2-2,. Data corresponding to the operation state is stored, and data corresponding to the operation state of the photoelectric sensor abnormality detection contact 24 b is stored in the photoelectric sensor abnormality detection contact region 244 b of the memory 244.

  Next, flowcharts showing the contents of various programs 24-2 for realizing the sensor abnormality diagnosis function are shown in FIGS. Here, the sensor abnormality diagnosing function has a high light emission amount state (for example, a 100% light emission amount state) and a low light emission amount state in each of the light projectors ST (1) to (M) of the one or more transmissive photoelectric sensors. Sensors that control the output data output to the output processing unit 22 so that the switching to (for example, the 50% light projection state) is repeated regularly, and that correspond to the high light projection state and the low light projection state, respectively. The input data from the input processing unit 21 is controlled so that the output is read repeatedly. When the sensor output captured in the high light projection amount state is “received light”, the sensor captured in the low light projection state. When the state in which the output is determined as “no light reception” continues for a predetermined number of times (in this example, twice), the transmission sensor is diagnosed as “sensor abnormal”.

  More specifically, the program 24-2 includes a projected light amount automatic switching program, a workpiece detection program, and a sensor abnormality determination program.

  FIG. 3A shows a flowchart showing the configuration of the light emission amount automatic switching program. As shown in the figure, in the automatic light projection amount switching program, the projectors ST (1) to (M) are turned on after the power is turned on. From each of the output terminals OUT (1) to (M) connected to the light projection amount switching terminals of the projectors ST (1) to (M) so as to alternately repeat the 50% light projection light amount state of (ms). The output processing unit 22 outputs the first logical value output signal corresponding to the 100% projected light quantity state and the second logical value output signal corresponding to the 50% projected light quantity state alternately and repeatedly. Is configured to control transmission of output data to (steps 101 to 104).

  Here, the parameter T (ms) that defines the duration of the 100% light emission amount state and the parameter t (ms) that defines the duration of the 50% light amount state are stored in the parameter storage memory 243. The These parameters {T (ms), t (ms)} can be arbitrarily set and monitored by a predetermined tool device via the tool I / F circuit 230.

  A flowchart showing the configuration of the workpiece detection program is shown in FIG. As shown in the figure, the workpiece detection program receives light that makes a pair with each of the projectors ST (1) to (M) when each of the projectors ST (1) to (M) is in a 100% projection light quantity state. When the sensor outputs of the instruments SR (1) to (M) are captured and the sensor output thus captured is a logical value corresponding to “with light reception” (NO in step 201), the workpiece detection contact is turned off while “light reception” When the logical value corresponds to “none” (YES in step 201), the workpiece detection contact is turned on.

  The ON / OFF data corresponding to the operation state of the workpiece detection contact obtained in this way is stored at a specified address (bit) in the workpiece detection contact area 244a of the work memory 244. The data stored in the work detection contact area 244a is, for example, waiting for the arrival of a predetermined transmission timing (including both timer management and event management) or when a transmission request arrives from the communication master unit 13. After waiting, it is sent to the communication master unit 13 by communication via the network 3, and further transferred to the CPU unit 12 via the transfer mediation memory by the input update process as described above, and thereafter executed in the user program. To be served.

  A flowchart showing the configuration of the sensor abnormality determination program (for the normal diagnosis mode) is shown in FIG. As shown in the figure, the sensor abnormality determination program indicates that when the sensor output captured in the 100% light projection state is “with light reception”, the sensor output captured in the 50% light projection state is “no light reception”. Is turned on for the photoelectric sensor abnormality detection contact 24b stored in the photoelectric sensor abnormality detection contact region 244b of the work memory 244 (step 301). 302, 306, 307, 308). On the other hand, when the sensor output captured in the 100% light projection state is “with light reception”, the state in which the sensor output captured in the 50% light projection state is determined to be “no light reception” does not occur at all. In this case, or if it happens once and does not continue twice or more, the photoelectric sensor abnormality detection contact 24b is turned off (step 305).

  Thereby, the photoelectric sensor abnormality detection contact 24b corresponding to each photoelectric sensor stored in the photoelectric sensor abnormality detection contact region 244b of the work memory 244 corresponds to the state of the photoelectric sensor at that time (sensor abnormal state, sensor normal state). Updated. As will be described later, the photoelectric sensor abnormality detection contact 24b waits for the arrival of a transmission response from the PLC or waits for the arrival of a predetermined transmission timing (including both timer management and an event). It is transmitted to the PLC side through the communication that passes.

  Next, an explanatory diagram of sensor abnormality diagnosis (normal diagnosis mode) using the slave of the present invention is shown in FIG. As shown in FIG. 6A, when the above-described automatic projection light amount switching program (see FIG. 3A) is operated, the sensor projection light amount is a duration T (ms) regardless of the presence or absence of a workpiece. ) And a 50% light projection state having a duration t (ms) are alternately and constantly repeated. In this state, the sensor output is “ON” when “work is present”, and the sensor output is “OFF” when “work is absent”. In addition, when the workpiece detection program (see FIG. 3B) is activated, the workpiece detection determination is performed only in the 100% light emission state, and as long as it is determined that the sensor output is ON at 100% light emission amount, The state of the workpiece detection contact is maintained until the 100% light emission amount state of the next cycle arrives. On the other hand, if it is determined that the “sensor output is OFF” in the 100% light emission state, the state of the workpiece detection contact is set to “OFF”. In addition, when the sensor output captured in the 100% light emission amount state is “ON”, the state in which the sensor output captured in the 50% light emission amount state is “OFF” does not continue more than twice. The state of the photoelectric sensor abnormality detection contact is kept “OFF”.

  On the other hand, when the photoelectric sensor is abnormal, as shown in FIG. 5B, when the sensor output read in the 100% light emission state is “ON”, the photoelectric sensor is in the 50% light emission state. When the state in which the read sensor output is “OFF” continues two or more times, the state of the photoelectric sensor abnormality detection contact changes from “OFF” to “ON”.

  As described above, according to the sensor abnormality diagnosis using the slave of the present invention (always diagnostic mode), the workpiece detection and the photoelectric sensor abnormality detection are always performed in parallel, and the workpiece detection contact 24a and the photoelectric sensor abnormality detection contact are performed. Since the state of 24b is updated every period determined by the length of the duration T (ms) of the 100% light emission amount state and the duration t (ms) of the 50% light emission state, the workpiece detection is performed on the PLC1 side. By referring to the states of the contact 24a and the photoelectric sensor abnormality detection contact 24b, it is possible to instantly recognize the presence or absence of a workpiece and the occurrence of a photoelectric sensor abnormality and take appropriate measures.

  If such a continuous diagnosis is to be realized with a conventional slave, timing generation processing for switching the sensor light amount, detection processing for detecting a workpiece from the sensor output while switching the projected light amount, and detection of a photoelectric sensor abnormality Since it is necessary to incorporate the process into the PLC user program on the user side, as the number of sensors increases, the user program capacity increases, the program becomes complicated, and the PLC cycle time increases. This will adversely affect the tact time of the system.

  On the other hand, if the slave of the present invention is used, the above-described timing generation processing, workpiece detection processing, and photoelectric sensor abnormality detection processing can be realized by control within the slave. There are various advantages such as the ability to detect sensor abnormalities and the ability to handle even when the distance between workpieces is small.

  In addition, when a workpiece is detected with a response as fast as possible, a small workpiece is detected, or the conveyor speed is high, it is preferable that the duration T (ms) in the 100% light projection state is long. In order to detect a sensor abnormality in a period corresponding to the interval, it is necessary to adjust so that the 50% light emission amount state is included twice or more in such a period.

  The duration T (ms) of the 100% light emission amount state and the duration t (ms) of the 50% light emission state are stored in the parameter storage memory 242 as described above, and can be remotely operated via a tool operation on the site or via a network. It can be arbitrarily changed or adjusted by the operation. Furthermore, if the number of repetitions of the 100% light emission state (ON) and the 50% light emission state (OFF) for determining that a sensor abnormality has occurred is stored in the parameter storage memory 243 as a parameter, this is stored in the field. It can be arbitrarily adjusted by operation or by remote operation through a network.

  The slave of the present invention can also cope with the maintenance mode. FIG. 5 shows a flowchart showing a configuration of a sensor abnormality determination program (for maintenance mode) incorporated in the slave of the present invention.

  For the maintenance mode, a light amount switch is provided for each slave. In the maintenance mode sensor abnormality determination program, when the contact of the light quantity change-over switch is OFF (step 401 OFF), in the 100% light emission state (step 402), “no light reception” ”Is determined (step 403 NO), the work detection contact is turned ON (step 404), and when“ received light ”is set (step 403 YES), the work detection contact is turned OFF (step 403). 405).

  On the other hand, when it is determined that the predetermined light amount change-over switch is ON (step 401 ON), “no light reception” in the state of the work detection contact OFF (step 406) and the 50% light emission amount state (step 407). Is determined (step 408 NO), the sensor abnormality detection contact is turned ON (step 409), and when it is “received light” (step 408 YES), the sensor abnormality detection contact is turned OFF (step 410).

  As described above, in the slave according to the present invention, since the sensor abnormality determination program for the maintenance mode is incorporated, the light quantity changeover switch is manually turned ON / OFF by selecting the period of no work in the maintenance mode. In addition, the sensor abnormality diagnosis can be performed.

  Next, a ladder diagram showing the configuration of the sensor abnormality detection output program (user program) incorporated in the PLC (used in both the normal diagnosis mode and the maintenance mode) is shown in FIG.

  As shown in the figure, when the slave of the present invention is used, in the user program on the PLC side, programming may be performed so as to refer to the contents of a series of photoelectric sensor abnormality detection contacts for each slave.

  In order for the PLC 1 to acquire the photoelectric sensor abnormality detection contact 24b from the slave 2, a predetermined transmission request command is transmitted from the PLC side to the slave side. On the slave side, the response of the photoelectric sensor abnormality detection contact is transmitted as a response. Without sending the contents to the PLC side or waiting for the arrival of a transmission request command from the PLC side, the photoelectric sensor abnormality detection contact is spontaneously transmitted from the slave side to the PLC side by an event or by timer management. It would be good to do. In any case, since several methods have already been established for the exchange of input / output data between the PLC and the slave, those methods may be appropriately adopted.

  Next, a ladder diagram (for maintenance mode) showing the configuration of a manual light quantity switching program (user program) incorporated in the PLC is shown in FIG. As described above, for the maintenance mode, it is only necessary to refer to the operation state of the light amount change switch of each slave and to program the output signal for light amount change from the corresponding slave on the condition. is there. In this case, the sensor abnormality detection program shown in FIG. 7 is used as it is.

  Next, an explanatory diagram of sensor abnormality diagnosis (diagnosis at power-on) using the slave of the present invention is shown in FIG. As shown in the figure, in this example, the slave itself performs a self-diagnosis when the system is started, and detects in advance whether or not an abnormality occurs in the photoelectric sensor. That is, when the system is started when the slave is powered on, it is usual that there is “no work”. Therefore, in such a state, between the 100% light emission amount state and the 50% light emission amount state. At least once, the amount of emitted light is switched, and the presence of light reception is confirmed in the 100% light emission state and “no light reception” is confirmed in the 50% light emission state. Then, the state of the photoelectric sensor abnormality detection contact is turned ON.

  Next, FIG. 10 shows an explanatory diagram of sensor abnormality diagnosis (when light cannot be received even with 100% light projection) using the slave of the present invention. The abnormality of the photoelectric sensor described so far was based on the premise that it can be determined that “there is light reception” in the 100% light projection state, but the optical axis is shifted or the lens is dirty to the extent that light cannot be received even in the 100% light emission state. If the LED is deteriorated or the LED is deteriorated, the sensor abnormality may be diagnosed on the condition that light cannot be received for a certain time U (ms) in the 100% light projection state. At this time, the fixed time U (ms) necessary for the determination may be arbitrarily adjusted by the user parameter setting.

  Next, FIG. 11 shows an explanatory diagram of sensor abnormality diagnosis using the slave of the present invention (when light cannot be received even with 100% light projection in the normal diagnosis mode).

  If light cannot be received even in the 100% light projection state, it may occur even in the normal diagnosis mode. In this case, it may be configured to diagnose the occurrence of sensor abnormality on the condition that light cannot be continuously received in a certain number of 100% light projection amounts. Here, the specific number of times required for the determination may be configured to be arbitrarily variably adjusted according to user parameter settings. In addition, the diagnosis method for the sensor abnormality that cannot be received even in the 100% light emission state is the above-described diagnostic method (normal diagnosis mode, maintenance mode) for the sensor abnormality that can receive light in the 100% light emission state and cannot receive light in the 50% light emission state. Needless to say, the self-diagnosis mode can be performed in parallel with the power-on self-diagnosis mode.

  According to the embodiment of the present invention described above, on the PLC 1 side, the contents of the sensor abnormality detection contact area 244b are simply displayed without giving an instruction for sensor abnormality diagnosis by switching the amount of emitted light to the slave 2 side. Since the operation state of the sensor abnormality detection contact 24b of each corresponding transmissive photoelectric sensor can be acquired simply by referring to it, in a sensing system in which a plurality of transmissive photoelectric sensors are connected to the PLC 1 via the slave 2, When the sensor abnormality diagnosis method using light quantity switching is performed, the burden on the user program on the PLC 1 side is remarkably reduced, and real-time photoelectric sensor abnormality detection is possible.

  In addition, the sensor abnormality diagnosis program included in the control unit has a high light projection state (for example, a 100% light projection state) and a low level in each of the light projectors ST (1) to (M) of one or more transmission photoelectric sensors. Output of output data to the output processing unit 22 is controlled so that switching to a light emission amount state (for example, a 50% light emission amount state) is constantly repeated, and a high light emission amount state and a low light emission amount state are controlled. The input data from the input processing unit 21 is controlled so that the corresponding sensor output is repeatedly read. When the sensor output captured in the high light output state is “received light”, in the low light output state. When the state where the acquired sensor output is “no light reception” continues for a predetermined number of times, the transmissive sensor diagnoses that the sensor is abnormal. The above-mentioned real-time photoelectric sensor abnormality detection is performed not only in the maintenance mode in which the operation of the controlled equipment is stopped and the flow of the work is stopped, but also during the operation of the controlled equipment. It becomes possible to do.

  Further, in the control unit, the sensor abnormality diagnosis program (see FIGS. 3 to 5) stores data corresponding to the determination result as to whether or not the sensor output captured in the high light projection amount state is not received. Since a work detection contact memory for storing the operation state of the work detection contact of the corresponding transmissive photoelectric sensor is further provided, the operation state of the work detection contact of each corresponding transmissive photoelectric sensor is regularly set on the PLC side. In addition to this, the operation state of the sensor abnormality detection contact of each corresponding transmissive photoelectric sensor can also be acquired, so that the sensor abnormality is diagnosed in parallel with the workpiece detection. It becomes possible.

  It should be noted that the percentage of the light projection light quantity state in each of the high light projection light quantity state and the low light projection light quantity state is determined by the specifications of the projector of the photoelectric sensor. Needless to say, it is not limited to the state. As an example of the slave operation method according to the present invention, for example, the entire sensor abnormality diagnosis program 24-2 is preinstalled on the manufacturer side at the time of shipment based on the specifications on the user side, while parameters T, t, etc. As for, it is conceivable that the user can arbitrarily rewrite it.

  According to the present invention, in a sensing system in which a plurality of transmission type photoelectric sensors are connected to a PLC via a slave, a sensor abnormality diagnosis method using projected light quantity switching is implemented. In addition to reducing the burden, it is possible to detect abnormality of the photoelectric sensor in real time.

It is a functional block diagram of this invention slave. It is a hardware block diagram of this invention slave. It is a flowchart which shows the structure of the light emission amount automatic switching program and workpiece | work detection program incorporated in this invention slave. It is a flowchart which shows the structure of the sensor abnormality determination program (for continuous diagnosis mode) integrated in this invention slave. It is a flowchart which shows the structure of the sensor abnormality determination program (for maintenance mode) incorporated in this invention slave. It is explanatory drawing of the sensor abnormality diagnosis (normal diagnosis mode) using this invention slave. It is a ladder diagram (combination of a normal diagnosis mode and a maintenance mode) showing a configuration of a sensor abnormality detection program incorporated in the PLC. It is a ladder diagram (for maintenance mode) which shows the composition of the manual light quantity switching program incorporated in PLC. It is explanatory drawing of the sensor abnormality diagnosis (diagnosis at the time of power-on) using this invention slave. It is explanatory drawing of the sensor abnormality diagnosis using this invention slave (when light cannot be received even with 100% light projection). It is explanatory drawing of the sensor abnormality diagnosis using this invention slave (when it cannot light-receive in 100% light emission in a normal diagnosis mode). It is a block diagram of the conventional sensing system which connected several transmission type photoelectric sensors to PLC via the slave. It is a functional block diagram of the conventional slave. It is a hardware block diagram of a conventional slave. It is explanatory drawing of the workpiece | work detection by a transmission type photoelectric sensor. It is explanatory drawing of abnormality diagnosis of the transmissive photoelectric sensor using the light quantity switching function. It is a ladder diagram showing a configuration of a slave-by-slave light quantity batch switching program incorporated in a PLC. It is a ladder diagram which shows the composition of the sensor abnormality detection output program built into PLC.

Explanation of symbols

1 PLC
2,2-1,2-2. ..., 2-N Slave 3 Network 11 Power supply unit 12 CPU unit 13 Communication master unit 14 I / O unit 21 Input processing unit 22 Output processing unit 23 Tool interface (I / F)
24 Control Unit 24-1 Parameter 24-2 Program (Abnormality Diagnosis Program)
24a Work detection contact 24b Photoelectric sensor abnormality detection contact 25 Communication processor 210 Input circuit 220 Output circuit 230 Tool interface circuit 241 MPU for control
242 Program storage memory 243 Parameter storage memory 244 Work memory 244a Work detection contact area 244b Photoelectric sensor abnormality detection contact 251 MPU for communication
252 Communication ASIC
253 Transceiver CV Conveyor ST Projector ST (1) to (M) Projector constituting the transmissive photoelectric sensor SR Receiver SR (1) to (M) Receiver comprising the transmissive photoelectric sensor W Workpiece

Claims (3)

A communication processing unit for exchanging input / output data with a PLC via a network;
One or more projection light quantity switching control terminals for switching the projection light quantity of each of the projectors of one or more transmissive photoelectric sensors between a high projection light quantity state and a low projection light quantity state, respectively. An output terminal block including an output terminal;
An input terminal block including one or more input terminals to be connected to each of the light receiving output terminals of each light receiver of the one or more transmissive photoelectric sensors;
An output processing unit that generates an output signal based on the given output data, and sends the output signal from the corresponding output terminal of the output terminal block to the outside;
An input processing unit that takes in an input signal input from the outside to an input terminal constituting the input terminal block and generates corresponding input data;
Including a control unit,
In the control unit,
Sending output data to the output processing unit so that each of the light projectors of the one or more transmissive photoelectric sensors is switched at least once between the high light emission amount state and the low light emission amount state. Control of the input data from the input processing unit so that the sensor outputs corresponding to the high and low light intensity states are read from each of the light receivers paired with each light emitter. Each of the transmission type photoelectric sensors based on whether the sensor output captured in the low light output state is “received light” or “no light received” when the sensor output captured in the high light output state is light received. Sensor abnormality diagnosing means for diagnosing whether or not is abnormal,
A sensor abnormality detection contact memory for storing data corresponding to a diagnosis result by the sensor abnormality diagnosis means as an operation state of an abnormality detection contact of each corresponding transmission type photoelectric sensor;
The sensor abnormality diagnosis means included in the control unit,
In each of the projectors of the one or more transmissive photoelectric sensors, the transmission of output data to the output processing unit is controlled so that the switching between the high light emission amount state and the low light emission amount state is regularly repeated. Controls the input data capture from the input processing unit so that the sensor output corresponding to each of the light emission amount state and the low light emission amount state is repeatedly read.
If the sensor output captured in the high light output state is “with light reception” and the sensor output captured in the low light output state is “with light reception” for a predetermined number of times, each transmission photoelectric sensor is normal. Diagnosed that there is,
If the sensor output captured in the high light output state is “with light reception” and the sensor output captured in the low light output state is “no light reception” for a predetermined number of times, each transmission photoelectric sensor is abnormal. To diagnose it,
Thereby, the PLC side does not give an instruction for sensor abnormality diagnosis by switching the amount of emitted light to the slave side, and simply refers to the contents of the sensor abnormality detection contact memory, and each corresponding transmission can obtain the operation state of the sensor abnormality detection contact type photoelectric sensor, further sensor abnormality Ru can constantly diagnose, PLC slave, characterized in that. In the control unit,
In the sensor abnormality diagnosing means, data corresponding to a determination result as to whether or not the sensor output captured in the high light emission amount state is “no light reception” is used for the operation of the workpiece detection contact of each corresponding transmission type photoelectric sensor. Work detection contact memory to store as status is further included,
Thereby, on the side of the PLC, the operation state of the work detection contact of each corresponding transmission type photoelectric sensor is constantly acquired, and together with this, the operation of the sensor abnormality detection contact of each corresponding transmission type photoelectric sensor is operated. The slave of the PLC according to claim 1, wherein the state can also be acquired. The sensor abnormality diagnosis means, PLC slave according to claim 1 or 2 automatically activated immediately after power-on of the slave, it is characterized.

Images