JP4816961B2 - Safety Remote I/O Terminal - Google Patents

Description

This invention relates to a safety remote I/O terminal that is connected to a safety programmable controller (hereinafter referred to as a safety PLC) via a network.

In addition to logic calculation functions and input/output control functions similar to those of general PLCs, safety PLCs incorporate a safety self-diagnosis function to ensure a high level of safety and reliability in their control. If an abnormality is detected as a result of self-diagnosis, the safety PLC has a function (fail-safe function) that forcibly performs safe control to prevent its own control from leading to danger.

More specifically, safety here includes standardized safety standards. Examples of safety standards include IEC 61508 and EN standards. IEC 61508 (International Electrotechnical Commission on Functional Safety of Programmable Electronic Systems) defines the probability of dangerous failure per hour (Probability of Failure per Hour) and classifies the SIL level (Safety Integrity Level) into four levels based on this probability. In addition, the EN standard requires that the level of risk of the machine be evaluated and measures to reduce the risk be taken, and EN 954-1 specifies five safety categories. The safety PLC and safety remote I/O terminals referred to in this specification correspond to one of these safety standards.

The basic configuration of such a safety PLC system is shown in FIG. 16. As shown in the figure, this safety PLC system is configured by connecting a safety PLC 1 and a safety remote I/O terminal 2 via a network 4. The safety remote I/O terminal 2 is provided with input terminals (IN0 to INn) and output terminals (OUT0 to OUTn). Input devices 5 and output devices 6 are connected to these input/output terminals. As is well known to those skilled in the art, examples of the input devices 5 include safety emergency stop switches, safety light curtains, safety limit switches, and safety door switches, while examples of the output devices 6 include safety relays and safety contactors.

The ON/OFF state of the input device 5 is sent to the safety PLC 1 as input data. The safety PLC 1 generates output data by executing a pre-programmed logic operation based on the received input data. The output data thus obtained is sent to the safety remote I/O terminal. The safety remote I/O terminal 2 receives the output data and controls the state of the output terminals (OUT0 to OUTn) based on the output data thus received. Through this series of data flows, the state of the output terminals (OUT0 to OUTn) is controlled.

That is, the ON/OFF states of the output terminals (OUT0 to OUTn) of the safety remote I/O terminal are uniquely determined by the contents of the output data transmitted from the safety PLC 1. Therefore, in order to control the states of the output terminals (OUT0 to OUTn) of the safety remote I/O terminal 2, it is always necessary to create some kind of calculation program on the safety PLC 1 side, which causes a problem that the calculation program on the safety PLC 1 side is inevitably complicated accordingly (see Patent Document 1).
JP 2006-304463 A

To solve the above problems, it is conceivable to incorporate an arbitrary calculation program into the safety remote I/O terminal 2 as well, and to output the output data generated based on the calculation program thus incorporated from the output terminals (OUT0 to OUTn) of the safety remote I/O terminal 2.

However, if an arithmetic program is also built into the safety remote I/O terminal 2 in this way, making it possible to generate output data independently, a problem arises as to how the output data thus obtained should be output to the output terminals (OUT0 to OUTn).

In other words, the output terminals (OUT0 to OUTn) on the safety remote I/O terminal 2 side are uniquely linked to the calculation program built into the safety PLC 1 side, so if the output data generated on the safety remote I/O terminal 2 side is inadvertently output to its own output terminals (OUT0 to OUTn), a conflict in output data will occur between the safety PLC 1 side and the safety remote I/O terminal 2 side.

If an output terminal dedicated to the terminal side is added to avoid such conflicts, this will increase the cost of the safety remote I/O terminal product and reduce the freedom of output terminal selection.

This invention was made with an eye on these conventional problems, and its purpose is to provide a new safety remote I/O terminal that allows any output data to be output from the safety remote I/O terminal without operating the calculation program of the safety PLC, and that avoids the increased costs associated with the addition of hardware by sharing the same output terminal between the safety PLC and the safety remote I/O terminal without causing output data conflicts between the two.

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

The above technical problems can be solved by a safety remote I/O terminal having the following configuration:

That is, this safety remote I/O terminal includes a communication circuit for communicating with the safety PLC via a network, one or more external output terminals to which output devices are respectively connected, an output circuit provided for each of the external output terminals and sending an output signal to the output device connected to the external output terminal, an output data storage means for local output data that stores output data to be sent to each of the output circuits, an output data storage means for communication-originated output data that stores output data for each output terminal received from the safety PLC via the communication circuit, an output data storage means for internally-originated output data that stores output data for each output terminal or common to all output terminals that is generated internally, an output function setting table storage means that rewritably stores an output function setting table that sets the output function of each external output terminal for each external output terminal, and an output function The device includes a local output switching means for referencing the setting contents of each external output terminal in the output function setting table stored in the setting table storage means, and when the setting contents are an output function that should output communication-originated output data, storing the communication-originated output data of the corresponding external output terminal stored in the output data storage means for communication-originated output data in a storage location of the corresponding external output terminal in the output data storage means for local-directed output data, while when the setting contents are an output function that should output internally-originated output data, storing the internally-originated output data of the corresponding external output terminal stored in the output data storage means for internally-originated output data in a storage location of the corresponding external output terminal in the output data storage means for local-directed output data, and an output refresh means for sending each output data stored in the output data storage means for local-directed output data to each output circuit of the corresponding external output terminal.

According to this configuration, the output data for each output terminal received from the safety PLC via the communication circuit is stored in the output data storage means for communication-originating output, and the output data for each output terminal or common to each output terminal generated internally is stored in the output data storage means for internally originating output data. However, unless the output data is stored in the output data storage means for local-directed output data by the action of the local output switching means, it is not sent to the corresponding external output terminal via the output refresh means. On the other hand, which output data should be stored in the output data storage means for local-directed output data is determined by the contents of the output function setting table for each external output terminal. Therefore, by appropriately setting the contents of this output function setting table according to the desired control specifications, a series of external output terminals can be used for communication-originating output data and internally originating output data. Therefore, the same output terminal can be shared arbitrarily between the safety PLC side and the safety remote I/O terminal side, and therefore costs due to the addition of terminal blocks can be avoided.

Here, various types of internally derived output data can be arbitrarily adopted. For example, if output data for each output terminal obtained as a result of executing a logic operation arbitrarily programmed within the device itself is adopted as the internally derived output data, the output data obtained as a result of executing an arbitrary logic operation can be output from any of the device's output terminals without manipulating the operation program on the safety PLC side. For this reason, for applications where communication is inappropriate due to the need for high-speed response, safety quality can be improved by executing the application via an internal logic operation.

In addition, if auxiliary output data common to each output terminal, which is generated by a predetermined process fixedly built into the device itself, is used as the internal output data, the user can output the desired auxiliary output data from any external output terminal simply by specifying or selecting the auxiliary output data, without having to write a special calculation program.

Various data can be used as such auxiliary output data. For example, if the same value output data of any output terminal is used as such auxiliary output data, it can be used in an application that displays the ON/OFF state of the contactor connected to the external output terminal on a notification lamp. If the inverted value output data of any output terminal is used as the auxiliary output data, it can be used in an application that provides an unlock signal for an electromagnetic lock safety door switch. If the output data for flashing a lamp to request a reset is used as the auxiliary output data, it can be used in an application for returning after the safety emergency stop switch is activated. If the output data corresponding to an operation mode flag indicating whether the terminal is in operation or not is used as the auxiliary output data, the program on the safety PLC side that was previously required for similar output becomes unnecessary. Furthermore, if the output data corresponding to a status flag indicating whether the terminal is in a normal state or not is used as the auxiliary output data, an application can be constructed in which the robot side operates when this signal is ON and stops when this signal is OFF by inputting such output data to the robot.

According to the present invention, internally generated output data can be output to any external output terminal of the device without competing with communication-derived output data coming from the safety PLC, which significantly improves the ease of use of this type of safety remote I/O terminal without increasing costs through hardware modifications such as adding additional terminal blocks.

Below, a preferred embodiment of the safety remote I/O terminal according to the present invention will be described in detail with reference to the attached drawings.

A schematic diagram of a safety PLC system to which the present invention is applied is shown in FIG. 1. As shown in the figure, this safety PLC system is configured by connecting a safety PLC 1, a safety remote I/O terminal 2, and a program development support device 3 configured by installing a specific tool software in a notebook computer, via a network 4.

As explained above, the safety PLC 1 is connected to an input device 5 and an output device 6, and the safety remote I/O terminal 2 is also connected to an input device 5 and an output device 6. Examples of these input devices include a safety emergency stop switch, a safety light curtain, a safety limit switch, a safety door switch, etc. Examples of the output devices 6 include a safety relay, a safety contactor, etc.

2 is a block diagram showing the electrical hardware configuration of the safety remote I/O terminal 2. As shown in the figure, the safety remote I/O terminal 2 has a communication circuit 204 for communicating with the safety PLC 1 (see FIG. 1) via the network 4, one or more external input terminals (IN0 to INn) to which input devices 5 are respectively connected, one or more external output terminals (OUT0 to OUTn) to which output devices 6 are respectively connected, an input circuit 202 provided for each external input terminal for inputting an input signal from the input device 5 connected to the external input terminal, and an output circuit 203 provided for each external output terminal for sending an output signal to the output device 6 connected to the external output terminal.

The display circuit 205 is composed of lamps and numeric displays that display the operating status of the terminal, and the setting circuit 206 is composed of DIP switches that are used to set the node address required for communication with the terminal.

The CPU 201 controls the entire terminal and includes a microprocessor (MPU) 201a, a ROM 201b, and a RAM 201c. In addition to various system programs for implementing the functions of the terminal, the ROM 201b stores various logic calculation programs arbitrarily programmed and incorporated by the user, and fixed programs for generating various auxiliary output data described below. The ROM 201b is partially composed of a non-volatile rewritable recording medium such as a flash memory, and stores an output function setting table described below, logic calculation programs arbitrarily created by the user, and other arbitrary data that can be rewritten by the user. The RAM 201c is used as a work area when the microprocessor (MPU) 201a executes various programs in the ROM 201b.

Next, FIG. 3 shows an explanatory diagram of the output function setting mode for each output terminal (OUT0 to OUTn). As shown in the figure, a first memory area (M1) is provided in the ROM 201b described above, and an output function setting table TB is stored in this first memory area (M1). This output function setting table TB sets the output function of each external output terminal (OUT0 to OUTn).

As shown in the figure, the output functions include output data from the safety PLC (output data derived from communication), logic operations (output data for each output terminal obtained as a result of executing logic operations arbitrarily programmed within the device), and auxiliary output (output data generated by the selection process of an auxiliary output function fixedly built into the device).

As will be described in detail later, this auxiliary output data includes equivalent output data of any output terminal, inverted value output data of any output terminal, output data for flashing a lamp to request a reset, output data corresponding to an operation mode flag indicating whether the terminal is in operation, and output data corresponding to a status flag indicating whether the terminal is in a normal state.

Next, FIG. 4 shows a memory map showing the configuration of the second to fifth memory areas deployed in a predetermined area of RAM 201c. As shown in the figure, the predetermined area of RAM 201c is provided with a second memory area (M2), a third memory area (M3), a fourth memory area (M4), and a fifth memory area (M5).

The second memory area (M2) functions as an output data storage means for local output data that stores the output data to be sent to each of the output circuits 203. As described below, the output data stored in this second memory area (M2) is sent to each of the output circuits of the corresponding external output terminals by executing an output refresh process.

The third memory area (M3) functions as an output data storage means for communication-derived output data that stores the output data for each output terminal (OUT0 to OUTn) received from the safety PLC 1 via the communication circuit 204.

In contrast, the fourth memory area (M4) and the fifth memory area (M5) function as output data storage means for internally derived output data that stores output data generated within the safety remote I/O terminal itself for each output terminal (OUT0 to OUTn) or common to all output terminals (OUT0 to OUTn).

The fourth memory area (M4) functions as an output data storage means derived from internal logic operations, which stores output data for each output terminal (OUT0 to OUTn) obtained as a result of executing logic operations arbitrarily programmed within the safety remote I/O terminal itself.

The fifth memory area (M5) functions as an output data storage means derived from auxiliary output calculations for storing auxiliary output data common to all output terminals (OUT0 to OUTn) generated by the selection process of the auxiliary output function fixedly incorporated inside the safety remote I/O terminal itself. Here, the auxiliary output data includes the same value output data of any output terminal, the inverted value output data of any output terminal, output data for flashing a lamp to request a reset, output data corresponding to an operation mode flag indicating whether the terminal is in operation or not, and output data corresponding to a status flag indicating whether the terminal is in a normal state or not.

Next, a general flowchart showing the processing of the safety remote I/O terminal is shown in FIG. 5. As shown in the figure, when processing is started by turning on the power, an operation mode control process (step 101) is first executed, and an operation mode transition process is executed to determine whether or not to transition to each of a number of pre-prepared operation modes.

Note that the illustrated example focuses on the case where RUN mode is selected as the operating mode, but if another mode is selected, the process corresponding to that mode is executed. In other words, within the group within the operating mode control process (step 101), there are branches that transition to the process for each mode depending on which mode is selected, but these are omitted from the diagram.

Next, an I/O refresh process (step 102) is executed. In this I/O refresh process, local input/output processing and diagnostic processing of the local input/output terminal are executed. This local input/output processing exchanges data between a pre-prepared memory area for local input (not shown) and a memory area for local output, i.e., in this example, the second memory area (M2), and the input device 5 and output device 6, thereby capturing the latest external input status into the memory area for local input and sending the latest local output to the external output terminal via the corresponding output circuit 6.

In the diagnostic process for the local input/output terminal, each of the input/output stages built into this type of safety remote I/O terminal is driven to perform diagnostic processing to check for faults such as burnt contacts or poor continuity in the input device 5 and output device 6.

In the subsequent communication process (step 103), the local output data stored in the second memory area (M2) is transmitted to the safety PLC 1 by communicating with the safety PLC 1 via the communication circuit 204, and output data sent from the safety PLC 1 is received and stored in the third memory area (M3). In the case of a conventional safety remote I/O terminal, the output data received from the safety PLC in this way is immediately sent to the corresponding external output terminal by the I/O refresh process (step 102) described above, but as will be described later, in the case of the present invention, the output data received from the safety PLC in this way is not necessarily sent to the external output terminal.

In the subsequent logic calculation process (step 104), logic calculation process, creation and update of equal value data and inverted value data, creation and update of reset request, and creation of local output data are executed.

In the logic calculation process, a logic calculation program that has been created in advance by the user and stored in the remote I/O terminal is executed, and logic calculation output data, which is the output data for each output terminal (OUT0 to OUTn) obtained as a result of the execution, is generated and stored in the memory location of the corresponding external output terminal (OUT0 to OUTn) in the fourth memory area (M4). The output data corresponding to the result of the logic calculation execution stored in the fourth memory area (M4) is transferred to the second memory area (M2) for local output data as necessary, and is finally sent to the corresponding external output terminal.

In addition, in the process of creating and updating the equivalent data and inverted value data, the equivalent data and inverted value data for the corresponding output terminal are created and updated based on the contents of the output function setting table TB, as described below.

In addition, in the process of creating and updating a reset request, output data for flashing a lamp to request a reset is created and updated using the process described below.

Furthermore, in the process of creating local output data, as will be described in detail later, the necessary data is obtained from the third memory area (M3), the fourth memory area (M4), and the fifth memory area (M5), and this is transferred to the second memory area (M2), thereby finalizing the local output data.

In the subsequent self-diagnosis process (step 105), various hardware diagnostic processes are performed on the remote I/O terminal, and the diagnostic results are stored.

If any serious abnormality occurs while repeating the above process (steps 101 to 105) (step 106: YES), the operation is immediately stopped.

Next, FIG. 6 shows a flowchart showing the details of the process for setting the output function for output terminal n for the output function setting table TB shown in FIG. 3. When the process is started in the figure, the following process is executed by deciphering the output function setting data sent from a program development support device (not shown) connected on the network (for example, see reference number 3 in FIG. 1). That is, if the deciphered output function is to output the output data from the safety PLC (as before), a predetermined code is stored as the content of the corresponding output terminal in the output function setting table TB stored in the first memory area (M1) as the output data from the safety PLC (step 202).

In addition, if it is determined that the contents of the decoded output function are output data determined by the execution result of the internally embedded logic operation program (step 201), a predetermined code is stored as the setting content of the corresponding output terminal in the output function setting table TB, indicating that the output data should be obtained as a result of the execution of the logic operation program (step 203).

On the other hand, if the contents of the decoded output function are judged to be an auxiliary output (step 201) and further judged to be the same as output terminal n, inverted with output terminal n, a reset request, an operation mode flag, or a status flag (step 204), the contents of the corresponding output terminal in the output function table TB are set to a predetermined code corresponding to such output data (steps 205, 206, 207, 208, 209).

In this way, the contents of the output function setting table TB stored in the first memory area (M1) shown in FIG. 3 can be rewritten at will according to the setting data from a program development support device connected to the network or directly connected to the remote I/O terminal.

As an example, Figures 14 and 15 show screen illustrations (part 1 and part 2) for setting the operation mode flag.

As is clear from these figures, a specified window is opened on the screen of the notebook computer that constitutes the program development support device, and a setting parameter list 400 is displayed in the window. In this setting parameter list 400, setting parameters related to the output function for each output terminal and their values are displayed, so that the user can select a specified parameter with cursor operation (see FIG. 14), operate pull-down button 401 to display parameter list 406, search for the required parameter value from there by operating scroll bar 405, position cursor 405 on the required parameter value, and operate OK button 402, thereby easily setting the required parameters and parameter values for each output terminal.

The output function setting data created in this way is sent to the remote I/O terminal via the network, making it possible to execute the output function setting process for output terminal n shown in Figure 6 above.

Next, a detailed flowchart of the process for determining the contents of the local output OUTm is shown in Figure 7. As shown in Figure 4, it is assumed that the second memory area (M2) stores local output data, the third memory area (M3) stores output data from the safety PLC, the fourth memory area (M4) stores output data obtained by internal logic operations, and the fifth memory area (M5) stores auxiliary output data such as a reset request, an operation mode flag, and a status flag.

In this state, when the process shown in FIG. 7 is started, the contents of the local output OUTm are determined for each output terminal number (m) in sequence. That is, first, the set output function of each output terminal is determined by referring to the contents of the output function setting table TB shown in FIG. 3, and depending on the result of the determination, the corresponding process (steps 303 to 309) is executed, thereby rewriting the output data in the second memory area (M2) corresponding to each output terminal (OUT0 to OUTn).

That is, if the settings in the output function setting table TB indicate that output data from the safety PLC should be output (step 302), the contents of the local output OUTm are overwritten by the output data OUTm from the safety PLC (step 303).

Also, if it is determined that the output function setting contents are determined by internal logic calculation (step 302), the contents of the local output OUTm are rewritten with the contents of the logic calculation output OUTm.

Also, if it is determined that the decoded setting contents are the same as the local output OUTn (step 302), the contents of the local output OUTn are overwritten with the contents of the local output OUTn.

Also, if it is determined that the output function of OUTm is the inverted value of OUTn, the contents of local output OUTm are rewritten as the inverted value of local output OUTn (step 306).

Also, if it is determined that the output function of OUTm is a reset request, the contents of the local output OUTm are rewritten to a reset request in the status data (step 307).

Furthermore, if it is determined that the output function of OUTm is an operation mode flag, the contents of the local output OUTm are rewritten as the operation mode flag of the status data (step 308).

Furthermore, if it is determined that the output function of OUTm is a status flag, the contents of the local output OUTm are rewritten as a status flag in the status data (step 309).

The above process is repeated from m=0 for the number of output points (step 311).

In this way, as a result of executing the process shown in the flowchart of FIG. 7, the contents of the local output data stored in the second memory area (M2) shown in FIG. 4 are rewritten with the contents of the third memory area (M3), fourth memory area (M4), and fifth memory area (M5) according to the settings of the output function setting table TB shown in FIG. 3. As a result, when the I/O refresh process (step 102) is executed in the general flowchart shown in FIG. 5, the local output data whose contents are stored in the second memory area (M2) is output to each of the actual external output terminals (OUT0 to OUTn).

Therefore, according to the remote I/O terminal of the above embodiment, by performing a predetermined operation on a program development support device (not shown) and appropriately setting the contents of the output function setting table TB shown in FIG. 3, a series of external output terminals (OUT0 to OUTn) can be made common, and each terminal can output output data derived from communication, output data derived from internal logic calculations, output data of the same value as an arbitrary output terminal, output data of the inverted value of an arbitrary output terminal, output data for a reset request, output data corresponding to an operation mode flag, and output data corresponding to a status flag. This significantly improves the usability of this type of remote I/O terminal, while at the same time providing the advantage that the output terminal block itself can be used as is without any significant increase in cost, even when such functions are added.

Next, applications suitable for each of the output functions described above will be explained with reference to Figures 8 to 13.

An explanatory diagram (part 1, part 2) of a safety control application suitable for the "equivalent output function" is shown in Fig. 8 and Fig. 9. In Fig. 8, 81 is a lamp for notifying the worker of various information, 82 is a safety light curtain installed at the entrance to the safety fence, 83 is a robot that is a source of danger, 84 is a worker, 85 is a reset switch for returning from an emergency stop state, and 86 is an emergency stop switch.

In a workplace like this, it is customary to turn on lamp 81 while robot 83, which is a source of danger, is in operation to notify the user that robot 83 is in operation. In such a case, the external terminal block of the remote I/O terminal is wired as shown in the wiring diagram in Figure 9(a).

In other words, simply put, contactor relays (KM1, KM2) are driven by outputting output signals (OUT0, OUT1) to terminals (23, 24). Redundant processing is performed by serially connecting the contacts (KM1, KM2) of the contactors (KM1, KM2) to the current path of the motor (M) that drives the robot. Furthermore, an output signal (OUT2) is output to terminal (25) to drive a lamp (L) (corresponding to lamp 81 in Figure 8).

In the conventional method, the lamp (L) is driven via a logic calculation program on the safety PLC 1 side. In contrast, in the present invention, the "equivalent output function" described above is used to output the output signal (OUT2) as an equivalent output to the terminal (25).

As a result, as shown in the timing chart of FIG. 9(b), the output signal (OUT2) for driving the lamp (L) turns on and off in synchronization with the output signals (OUT0, OUT1) for driving the contactors (KM1, KM2). At this time, for example, the output signal OUT2 is defined to have the same value as the output signal OUT0. This makes it possible to realize the lighting operation of the lamp (L) without going through the control on the safety PLC1 side.

An explanatory diagram of a safety control application suitable for the "reset request output function" is shown in FIG. 10. As explained with reference to FIG. 8, this type of work site is provided with lamps 81 to inform the worker 84 of various situations. If the operation of the robot 83 is stopped by operating the emergency stop switch 86, the robot cannot return to its original state unless the reset switch 85 is operated for safety reasons. At this time, to ensure that the worker 84 does not forget to operate the reset switch 85, the lamp 81 is caused to flash by sending out a reset request signal, which is an oscillating output, while waiting for the operation of the reset switch 85.

As shown in FIG. 10, in order to drive the lamp to blink, a reset request signal, which is an oscillation output of a specified frequency, must be sent out. Conventionally, this reset request signal was generated by writing a specified program on the safety PLC 1 side, but the processing was quite complicated. In contrast, in the present invention, an oscillation output equivalent to a reset request can be generated as shown in FIG. 10(d) for a certain period determined by the output of the emergency stop switch shown in FIG. 10(a) and the output of the reset switch shown in FIG. 10(b), and this can be set in the output function setting table TB as a "reset request," making it possible to output this reset request from any external output terminal. This allows the lamp 81 to be driven to blink by outputting a reset request from the remote I/O terminal without going through the safety PLC 1.

The diagrams (part 1 and part 2) of a safety control application suitable for the "reverse output function" are shown in Fig. 11 and Fig. 12. In Fig. 11, 84 is an operator, 86 is an emergency stop switch, 87 is an electromagnetic lock safety door switch, 88 is a hazard source, and 89 is a limit switch.

When the dedicated operation key is inserted, the electromagnetic lock safety door switch automatically becomes mechanically locked, and the door cannot be opened. When voltage is applied to the solenoid at this time, the lock is released and the door can be opened. For example, as shown in FIG. 12(a), a contactor output is sent to the output signals (OUT0, OUT1) and an unlock signal for the electromagnetic lock safety door switch is output as the output signal (OUT2). Then, as shown in the time chart in FIG. 12(b), if the unlock signal is to be obtained after the contactor output turns OFF, simply by setting "output terminal 0 and inverted output" for the output signal (OUT2) of the remote I/O terminal, no programming is required on the safety PLC1 side.

An explanatory diagram of a safety control application suitable for the "status flag output function" is shown in FIG. 13. As shown in FIG. 13, if an output signal corresponding to a status flag is sent from any output terminal of the safety remote I/O terminal 2, safety control can be realized by making the output signal corresponding to this status flag an operating condition on the robot 7 side. With this configuration, whereas in the conventional example shown in FIG. 13(b), it was necessary to send a signal corresponding to such a status flag to the robot 7 via a dedicated cable without any communication from the safety PLC 1, such a cable is no longer necessary, improving usability.

According to the present invention, internally generated output data can be output to any external output terminal of the device without competing with communication-derived output data coming from the safety PLC, which significantly improves the ease of use of this type of safety remote I/O terminal without increasing costs through hardware modifications such as adding additional terminal blocks.

1 is a schematic configuration diagram of a safety PLC system to which the present invention is applied; FIG. 2 is a block diagram showing an electrical hardware configuration of the safety remote I/O terminal. 4 is an explanatory diagram of an output function setting mode for each output terminal (OUT0 to OUTn). FIG. 11 is a memory map showing the configuration of second to fifth storage areas. 4 is a general flowchart showing the processing of a safety remote I/O terminal. 13 is a detailed flowchart of an output function setting process for an output terminal n. 11 is a detailed flowchart of a process for determining the contents of a local output OUTm. This is an explanatory diagram (part 1) of a safety control application suitable for the "equivalent output function." This is an explanatory diagram (part 2) of a safety control application suitable for the “equivalent output function.” FIG. 11 is an explanatory diagram of a safety control application suitable for the "reset request output function." FIG. 1 is an explanatory diagram (part 1) of a safety control application suitable for the “inverted output function.” FIG. 2 is an explanatory diagram (part 2) of a safety control application suitable for the “inverted output function.” FIG. 11 is an explanatory diagram of a safety control application suitable for the "status flag output function." FIG. 11 is a screen explanatory diagram (part 1) for setting an operation mode flag for output 2. FIG. 2 is a second explanatory diagram of a screen when setting an operation mode flag for output 2. FIG. 1 is a basic configuration diagram of a safety PLC system.

Explanation of symbols

1. Safety PLC
2 Safety remote I/O terminal 3 Program development support device 4 Network 5 Input device 6 Output device 7 Robot 81 Notification lamp 82 Safety light curtain 83 Robot 84 Worker 85 Reset switch 86 Emergency stop switch 87 Electromagnetic lock safety door switch 88 Hazard source 89 Limit switch 201 CPU
201a Microprocessor (MPU)
201b ROM
201c RAM
202 Input circuit 203 Output circuit 204 Communication circuit 205 Display circuit 206 Setting circuit 400 Parameter list 401 Pull-down button 402 OK button 403 Cancel button 404 Scroll bar 405 Cursor KM1, KM2 Contactor M Motor M1 First storage area M2 Second storage area M3 Third storage area M4 Fourth storage area M5 Fifth storage area L Lamp OUT0 to OUTn External output terminals TB Output function setting table

Claims (8)

a communication circuit for communicating with the safety PLC via a network;
One or more external output terminals to which output devices are respectively connected;
an output circuit provided for each of the external output terminals, for transmitting an output signal to an output device connected to the external output terminal;
an output data storage means for storing output data to be sent to each of the output circuits;
an output data storage means for storing output data for each output terminal received from the safety PLC via a communication circuit;
an output data storage means for storing output data of internal origin, the output data being generated internally for each output terminal or being common to all output terminals;
an output function setting table storage means for rewritably storing an output function setting table for each of the external output terminals, the output function of which is set for that external output terminal;
a local output switching means for referencing the setting contents of each external output terminal in an output function setting table stored in an output function setting table storage means, and when the setting contents are an output function for outputting communication-originated output data, storing the communication-originated output data of the relevant external output terminal stored in the output data storage means for communication-originated output data in a storage location of the relevant external output terminal in the output data storage means for local-directed output data, while when the setting contents are an output function for outputting internal-originated output data, storing the internal-originated output data of the relevant external output terminal stored in the output data storage means for internal-originated output data in a storage location of the relevant external output terminal in the output data storage means for local-directed output data;
and output refresh means for transmitting each output data stored in the output data storage means for local output data to each output circuit of a corresponding external output terminal. The safety remote I/O terminal according to claim 1, characterized in that the internally derived output data is output data for each output terminal obtained as a result of executing a logic operation arbitrarily programmed within the terminal itself. The safety remote I/O terminal according to claim 1, characterized in that the internally derived output data is auxiliary output data common to each output terminal, which is generated by a predetermined process fixedly embedded in the terminal itself. The safety remote I/O terminal according to claim 3, characterized in that the auxiliary output data is equivalent output data of any output terminal. The safety remote I/O terminal according to claim 3, characterized in that the auxiliary output data is inverted value output data of any output terminal. The safety remote I/O terminal according to claim 3, characterized in that the auxiliary output data is output data for flashing a lamp to request a reset. The safety remote I/O terminal according to claim 3, characterized in that the auxiliary output data is output data corresponding to an operation mode flag indicating whether the terminal is in operation or not. The safety remote I/O terminal according to claim 3, characterized in that the auxiliary output data is output data corresponding to a status flag indicating whether the terminal is in a normal state or not.

Images