Controller and tool

The present invention relates to a controller that repeatedly executes a user program instruction execution and one cycle of processing including communication processing, and a tool for the controller.

A programmable controller (PLC) is used as a control device for factory automation (FA) installed in a production factory (manufacturing site). Input devices such as switches and sensors and output devices such as motors and actuators are connected to this PLC directly or via a network. The PLC calculates and executes a user program composed of a user program description language (for example, a ladder language) registered in advance based on the input data acquired from the input device, and controls the operation of the output device based on the obtained output data. ..

Further, the PLC is connected to another PLC, a higher-level computer (monitoring device, management device), a programmable display, etc. via a network, and has a function of performing communication processing with those external devices. The communication process is not limited to the above-mentioned external device, but may be performed with an input device or an output device.

Figure 1 shows the relationship between the calculation execution of the above user program and the communication processing. That is, the PLC makes one cycle of "ladder instruction execution processing (performs operation of the user program)" "communication processing" "other processing", and executes it cyclically and repeatedly. The time required to execute one cycle is called the scan time. Then, in the communication process, one packet is sent per cycle. This suppresses fluctuations in the scan time.

<p> However, the above-mentioned conventional communication processing for one packet per cycle has the following problems. In other words, there is not much problem with serial communication with slow transmission speed, which has been generally used in the past, but with PLCs in recent years, it has become possible to connect to networks with high transmission speed such as Ethernet (registered trademark), so all at once. Targets to be subjected to communication processing may be concentrated, such as receiving a large number of communications (packets) and returning a response to them.</p><p> Even in such a case, only one packet can be processed per cycle, so if there are N packets to be processed at about the same time, they will be processed with a delay of up to N cycles. As a result, rapid communication processing becomes impossible. Furthermore, as the scan time increases (compared to that shown in FIG. 1), for example, as shown in FIG. 2, the above problem becomes more prominent.</p><p> On the other hand, in order to solve such a problem, there is also one that defines the packet processing amount (PPS: Packet Per sec) per second. In this case, if the packet to be processed for communication exists, the communication processing is sequentially performed at the defined interval. Therefore, as shown in FIG. 3, the execution of the ladder instruction may be interrupted and the communication process may be performed a plurality of times during one cycle.</p><p> The number of communication processes that occur in one cycle varies depending on the number of packets to be processed for communication that are accumulated at that time, and may be 0 times, multiple times, or many times. Since the scan time changes depending on the number of times communication processing occurs, it cannot be uniquely defined and cannot be applied to a user who wants to keep the scan time n at a certain time.</p><p> Further, in both the above-mentioned method of fixing the communication processing per cycle with one packet (see Fig. 1 and Fig. 2) and the method of fixing the packet processing amount per second (see Fig. 3), the system It was a setting and could not be easily changed by the user. An object of the present invention is to provide a controller and a tool that allow a user to arbitrarily set the communication performance of communication processing in a controller.</p>

<p> The controller of the present invention is a controller that repeatedly executes a user program instruction execution and one cycle of processing including communication processing, and is a communication condition storage means for storing communication conditions that define the communication performance of the communication processing. A means for executing the communication process is provided according to the communication performance stored in the communication condition storage means, and the communication performance stored in the communication condition storage means can be set based on an external command.</p><p> Here, the controller includes not only a programmable controller and other control devices, but also components such as a CPU unit.</p><p> The communication performance is a performance capable of performing communication processing per cycle, and the higher the communication performance, the more the communication processing target such as each packet can be transmitted without delay, but the scan time required for one cycle is longer. The longer the communication performance and the lower the communication performance, the shorter the scan time can be. However, when the communication processing targets are concentrated, a large delay occurs before the actual transmission. In the present invention, since the communication performance stored and retained by the controller can be set by an external command, each user sets an appropriate communication performance in consideration of the balance between the above communication performance and the switch time, and the user's own usage condition. It becomes an appropriate operating state according to.</p><p> The communication performance can be specified and set in various ways. For example, it depends on the packet processing time per cycle, the packet processing amount per cycle, the ratio to the scan time required for one cycle, and the like. Can be specified.</p><p> It is preferable that a measuring means for measuring the scan time required for performing the one cycle is provided, and the measured value of the scan time obtained by the measuring means can be output to the outside. This output to the outside may be voluntarily sent to the outside (for example, a tool) triggered by the measurement of the scan time, or the measured value may be output as a response to a command (command) from the outside. Often, contrary to the above, it may be stored in a memory area accessible from the outside so that it can be accessed and acquired from the outside. If the measured value of the scan time is known, it is possible to evaluate whether or not the set communication performance is appropriate, and if it is inappropriate, it can be used as a reference when updating the communication performance.</p><p> The tool according to the present invention is a tool for a controller that repeatedly executes a user program instruction execution and one cycle of processing including communication processing, and acquires the communication performance of the communication processing in response to input from the user. A means and a setting means for setting the acquired communication performance in the controller are provided.</p><p> In the embodiment, the acquisition means is a function of displaying a setting screen such as FIG. 7 or FIG. 8 or receiving an input, and corresponds to a functional portion for executing S11 to S15 or the like. Further, the setting means corresponds to S16 and the functional portion for executing FIG. 10 in the embodiment.</p><p> It is preferable that the input of the communication performance from the user is relative information such as low and high, and that the relative information is converted into specific numerical information and set in the controller. In this way, the communication performance can be set as if the user were.</p><p> It is preferable to have a means for acquiring a scan time when the controller operates based on the communication performance set by the setting means for the controller, and a function for outputting the acquired scan time to the output means. The acquisition means may be such that the set controller is actually operated and the scan time of the measured value in that case is acquired, or it may be calculated and estimated by a theoretical value or the like.</p>

<p> In the present invention, the user can arbitrarily set the communication performance of the communication processing in the controller.</p>

FIG. 4 shows a preferred embodiment of the present invention. The CPU unit 10 that constitutes the PLC and the tool 20 are connected via a network. In the illustrated example, the CPU unit 10 and the tool 20 are directly connected, but they can also be connected via another network to which the PLC is connected. That is, the PLC is configured by appropriately connecting units that execute various functions, such as a power supply unit, an IO unit, and a communication unit, in addition to the CPU unit 10. In such a case, the tool 20 may be connected to the network to which the communication unit is connected, and the tool 20 may access the CPU unit via the communication unit.

Further, the communication partner of the CPU unit 10 is described by taking the tool 20 as an example in the present embodiment, but communication with the CPU unit of another PLC can also be applied. As a result, distributed control and the like can be performed. When a plurality of PLCs exist in this way, the tool 20 can set communication processing for each of the CPU units of the plurality of PLCs connected to the network.

The PLC is not limited to connecting a plurality of units as described above, and there is also an integrated type in which all necessary functions are mounted in one housing, and the present invention is also applied to such a type. it can.

The CPU unit 10 is one of the components of the PLC. Then, the system program for performing the original cyclic processing operation of the CPU unit 10 is stored in the system ROM 11. Then, the MPU 12 executes a predetermined process according to the system program of the system ROM 11 while appropriately using the system RAM 13 as the work memory. Further, during the operation of the PLC, the user program created in advance by the user using the programming tool is stored in the user memory 14. Further, I / O data and parameters used for logical operations of user program execution are stored in the IO memory 15. Then, the CPU unit 10 takes in IN data from the I / O unit (not shown) connected via the PLC system bus in the IN refresh process before the user program execution process. Then, in the logical operation processing in the CPU unit 10, a logical operation is performed based on the IN data, and the logical operation result is output to the I / O unit as OUT data in the OUT refresh processing.

The user program execution process in the CPU unit 10 is performed by the MPU 12. When the MPU 12 enters the user program execution process, the MPU 12 sequentially calls and executes the user program stored in the user memory 14.

The communication interface 16 sends / receives data to / from the tool 20. The communication interface 16 in this embodiment supports a high-speed network such as Ethernet (registered trademark). Through this communication interface 16, the tool 20 monitors the I / O data of the CPU unit 10, uploads the user program stored in the user memory 14, and applies the edited user program to the user memory 14. Download and make various settings. Communication processing with this tool 20 is performed, for example, by peripheral processing of cyclic processing in the CPU unit 10.

Here, in the present embodiment, the user program is constructed in the ladder language, and the above logical operation (logical operation processing) is equivalent to the execution of the ladder instruction. Then, as shown in FIG. 5, the MPU 12 cyclically and repeatedly executes the ladder instruction execution, the communication processing, and other processing (peripheral processing) as one cycle as in the conventional case. The communication processing in the present embodiment is performed via the communication interface 16 built in the CPU unit 10. In addition, other processing includes processing for exchanging data between the PLC and the personal computer tool via Ethernet (registered trademark), for example, higher-level communication protocol processing, data access processing (model read, state read, variable). Monitor etc.) etc. Specifically, the tool reads the memory area of the PLC. The data to be read includes scan time, error count, execution count, total execution time, and the like. Communication of I / O data used for control is performed by equipping each PLC with a control communication unit and performing controller link communication with it.

The task management unit 12a manages the execution of the ladder instruction, the communication process, and other processes. That is, the function of executing the ladder instruction, the function of performing communication processing, and the function of performing other processing are implemented in MPU12 and are executed as tasks respectively. Therefore, the task management unit 12a first executes a task for executing the ladder instruction, and sequentially executes the instruction from the first line to the last line of the user program stored in the user memory 14. After executing up to the last line, the task that performs communication processing is then executed. When the desired communication process is executed, a task for performing other processes is executed. For other processes, an upper limit value (ratio to the scan time) is set in advance, and the process ends when the upper limit value is reached. By sequentially performing such processing (switching of execution tasks), one cycle of processing as shown in FIG. 5 is repeated.

Although not shown in the figure, IN refresh and OUT refresh processing are performed as the ladder instruction is executed. As an example, after executing the ladder, IN refresh / OUT refresh can be performed, and then communication processing can be performed. Therefore, it may be considered that IN refresh / OUT refresh processing is included in the execution of the ladder instruction.

Here, in the present invention, the execution condition (communication condition) of the communication process can be changed by the user's setting. Specifically, in the present embodiment, the processing time (t1 [μsec]) of a packet having one scan time value can be arbitrarily set. The specific value of t1 is registered in the communication condition storage area 14a, which is a predetermined storage area in the user memory 14 that can be written by using the tool 20. Then, for example, the task management unit 12a accesses the communication condition storage area 14a, acquires the registered processing time t1, executes the communication processing execution task, and if t1 [μsec] elapses after the operation, the communication processing Stops the task that executes, and controls the task that executes other processing to run. Further, the task itself that executes the communication process may acquire the processing time t1, and when the communication process is executed for the set processing time, the processing of that time may be terminated. In the present embodiment, the communication condition storage area 14a is allocated to the user memory 14, but the present invention is not limited to this, and the communication condition storage area 14a may be a storage area accessible to the user.

As described above, since the communication condition storage area 14a for storing the processing time t1 allocates an area in the user memory 14 accessible to the user, the user can freely set the communication condition storage area 14a by using the tool 20. Therefore, for example, a user who wants to avoid delay in communication although the scan time n1 may be long may set a long processing time t1 and conversely, may send communication but want to shorten the scan time n1. By setting t1 short, the user can easily construct a PLC that operates under the communication conditions that meet the specifications of each user.

Further, the communication conditions are not limited to those in which the packet processing time is variable as described above, and for example, as shown in FIG. 6, the number of packets p1 to be communicated may be changed. In other words, it changes the packet processing amount per scan time, giving priority to increasing the scan time n1 by setting p1 = 1 [packet] as in the past, or conversely setting multiple p1s for communication processing. Can be prioritized. Further, even when the communication process is prioritized, it is possible to set the specifications desired by the user by setting the degree to a desired value by appropriately setting the numerical value.

Furthermore, the communication condition can be set by a relative value such as a ratio to the scan time n1 (for example, 10%) instead of setting it as an absolute value such as the time t1 or the number of packets p1.

Next, a tool 20 for easily setting the above communication conditions by the user will be described. As shown in FIG. 4, the tool 20 has a configuration in which the input unit 21, the memory 22, the MPU 23, the display unit 24, and the communication interface 25 are connected via the internal bus 26. The input unit 21 includes a keyboard for inputting various conditions, a pointing device, and the like. Further, the display unit 24 is composed of a display, and in relation to the present invention, has a function of displaying a condition input screen on the display screen of the display and prompting the user to input the condition.

The communication interface 25 is for communicating with the PLC (CPU unit 10). When it is directly connected to the CPU unit 10, it becomes an RS232C compatible interface, for example, and when it is connected to the PLC communication unit, it becomes the interface. The interface is compatible with the network to which the communication unit is connected (Ethernet (registered trademark), etc.).

The memory 22 is shown as one block in the figure, but in reality, it is a non-volatile memory that stores system programs, display screen templates, a list of setting conditions, etc., and a work memory during MPU23 calculation execution. There is a volatile memory that can be used as a template.

For example, the MPU23 outputs and displays the communication condition setting screen as shown in FIGS. 7 and 8 on the display unit 24, and sets the packet processing time based on the pull-down menu. At this time, there is a method of specifying a specific absolute value, but it is difficult for the user to specify a specific absolute value. Therefore, by inputting abstract information such as "high", "medium", and "low", the tool can change the specific time and number of packets, and download the converted value to the PLC. did. Then, specifically, the flowcharts shown in FIGS. 9 and 9 are executed.

First, set the PLC system setting mode (S11) and select the communication setting (S12). That is, first, in the process of S11, when it is recognized that the user has selected the system setting mode from the menu screen displayed on the display unit 24, the setting screen for performing various settings as shown in FIG. 7 is displayed. (Actually, the "general setting screen" in Fig. 7, which is also the front page, is displayed as the initial screen). Next, the user selects an arbitrary item in this setting screen and sets various parameters and the like. However, in relation to the present invention, the communication condition setting screen is on the "Ethernet" screen. , The user will click on the "Ethernet" column. Therefore, in the processing of S12, it is detected that the relevant "Ethernet" column is clicked, and the corresponding screen is switched and displayed (see FIG. 7).

Next, the input screen of the communication performance (here, the processing time) is displayed (S13). That is, when it is detected that the "advanced setting" in the group on the left column side is clicked on the screen shown in FIG. 7, the parameter input screen shown on the right column side is displayed. The "communication bandwidth" column on this input screen is a column for designating the communication processing time. In this example, the pull-down menu method is used to select from three types: low, medium, and high. Here, "low" corresponds to 400 μsec, "medium" corresponds to 1.6 msec, and "high" corresponds to 3.2 msec2. Of course, you may enter a specific numerical value, but if the user does not have a fixed term of what is the standard as a specific numerical value, you will not be able to enter an appropriate numerical value, so "Low / Medium / I made it easier to understand sensuously, such as "high".

Since the user selects one of the three communication speeds using the pull-down menu, the MPU23 acquires which speed is selected (S14). Then, the selected speed is displayed. That is, when the user sets the communication bandwidth (packet processing time) to "high" from the state shown in FIG. 7, the communication bandwidth column is displayed as "high" as shown in FIG. Actually, the one selected in the menu list is displayed.

In this state, if it is detected that the "OK" button or "Apply" button prepared at the bottom of the setting screen is clicked, the communication bandwidth selected at that time is confirmed as the communication setting content (S15). ). In this embodiment, since it is premised that the packet processing time is changed and set, the communication bandwidth is suddenly input. However, for example, a plurality of types of communication conditions such as the number of packets and the ratio are prepared. , If the user is allowed to select any of them, a selection screen of the relevant type is also prepared. Even in that case, it is preferable to select the communication bandwidth from a plurality of stages such as "low / medium / high" and associate the number of packets and the ratio with each of them. Further, since the number of packets is currently fixed at one packet, a numerical input may be allowed.

Then, the content (processing time) of the communication setting confirmed by the above processing is sent to the PLC (CPU unit) and set (S16). This setting process is performed by executing the flowcharts shown in FIGS. 10 and 11 between the tool 20 and the PLC (CPU unit 10).

That is, first, on the tool side, as shown in FIG. 10, the PLC mode is monitored (S21), and whether or not it is the program mode is determined (S22). Then, when it is not in the program mode (RUN mode), a command to switch to the program mode is transmitted (S23). As a result, when the processing of S24 is executed, the PLC side has completed the switching to the program mode, so that the communication setting contents are transmitted to the PLC (S24). The communication setting content (communication condition) to be sent at this time will be a specific numerical value (obtained by referring to the correspondence table prepared in advance) corresponding to any of "low, medium, high" specified by the user. ..

As shown in FIG. 15, on the PLC (CPU unit 20) side, the tool 20 side switches to the program mode by performing at least S23 processing (S31). After that, wait for the communication setting change command from the tool 20 (S32). Then, when the communication setting is received, the setting is updated to the received content (S33). As a result, the content of the acquired communication setting, that is, the specific packet processing time is stored in the communication condition storage area 14a of the user memory 14.

After updating the settings, MPU12 of CPU unit 10 is restarted by resetting the power supply (S34) and switched to RUN mode (S35). Then, based on the updated packet processing time, a series of processing such as ladder instruction execution, communication processing, and other processing is executed (S35). At this time, the scan time measuring unit 12b actually measures the scan time n1 taken (S36). Then, the scan time n1 obtained by actual measurement is sent to the tool 20. After that, normal cyclic processing is performed (S37).

The scan time measurement unit 12b continuously measures and stores the scan time n1 even when the normal cyclic process is executed. Further, the measured value n1 obtained in S36 above may be spontaneously transmitted from the CPU unit 20 side, but may be passed to the tool 20 side as a response in response to a request from the tool 20.

On the other hand, the tool 20 sends the communication setting contents of S24 to the PLC, and then waits for the scan time n1 to be sent from the PLC (CPU unit 20) side (S25). Then, when the scan time n1 is received, the scan time (cycle time) n1 is displayed on the display unit 24 (S26), and permission from the user is awaited.

The user looks at the scan time displayed on the display unit, determines whether or not the scan time is acceptable, operates the input unit 21, and inputs the determination result. Therefore, when the MPU23 receives an instruction for permission from the user (Yes in the branch judgment of S27), the MPU23 ends the setting (S28). In addition, when it receives a disapproval instruction (No in the branch judgment of S27), it resets (S29). That is, the flowchart of FIG. 9 is executed.

In the above-described embodiment, as shown in the flowchart shown in FIG. 10, the S24 process is performed, the communication setting contents are once sent from the tool 10 to the PLC, and then from the PLC as in the processing steps from S25 to S29. The present invention is not limited to this, although the function of waiting for the reception of the cycle time of the above and prompting the possibility of resetting is provided. That is, for example, the processing on the tool side can be temporarily terminated by executing the S24 processing, and a human can check the operating state (response accuracy) of the PLC and reset it if necessary. The resetting in this case can be dealt with by executing, for example, the flowchart shown in FIG.

In the above-described embodiment, the scan time n1 is actually measured, the result is displayed on the display unit 23 of the tool 20, the user is made to judge the length (appropriateness) of the scan time n1, and the scan time n1 and the communication process are adjusted. However, in the present invention, it is not always necessary to display the scan time n1. Further, even when displaying, the tool may calculate an estimated value of the scan time based on the number of instructions of the user program and display it instead of actually measuring it.

Further, when the ratio is used as the setting of the communication process, for example, the time required for executing the ladder instruction is estimated based on the number of instructions of the user program, the time required for other processes is set as a fixed value, and the communication process is performed. This can be achieved by calculating the processing time that is the ratio of the time set as a variable and notifying it as the communication setting content. In addition, once the communication processing time is set to 0, one cycle of processing is executed, the desired ratio is obtained based on the actually measured scan time n1 at that time, the communication processing time is obtained, and this is notified as the communication setting content. Various measures can be taken, such as.

<figref num="1">It is a figure which shows the conventional example.</figref><figref num="2">It is a figure which shows the conventional example.</figref><figref num="3">It is a figure which shows the conventional example.</figref><figref num="4">It is a figure which shows one Embodiment of this invention.</figref><figref num="5">It is a figure explaining the operation of this embodiment.</figref><figref num="6">It is a figure explaining the operation of this embodiment.</figref><figref num="7">It is a figure which shows an example of the condition setting screen.</figref><figref num="8">It is a figure which shows an example of the condition setting screen.</figref><figref num="9">It is a flowchart which shows the function of a tool.</figref><figref num="10">It is a flowchart which shows the function of a tool.</figref><figref num="11">It is a flowchart which shows the function of PLC (CPU unit).</figref>

Code description

10 CPU unit 11 System ROM 12 MPU12a Task management unit 12b Scan time measurement unit 13 System RAM 14 User memory 14a Communication condition storage area 15 IO memory 16 Communication interface 20 Tool 21 Input unit 22 Memory 23 MPU24 Display unit 25 Communication interface 26 Bus