CPU is the core part of the PLC system for the management and control of the full-automatic wrapping film packaging machine. It needs to manage the peripheral devices such as the programmer, self diagnose the system, compile the user program, operate the input and output, execute the user program, etc. It is impossible for the CPU of the full-automatic winding film packaging machine to complete several functions at the same time, so it must be processed in time. Today, let’s take a look at the working principle and workflow of the CPU of the full-automatic winding film packaging machine?
1、 Work flow of CPU of automatic wrapping film packaging machine
After the operation system of the full-automatic wrapping film packaging machine is powered on, the CPU first performs initialization work, including clearing the I / O Relay area and resetting all timers for the execution of user programs. Then check the I / O unit connected in the system and compare it with the I / O registration table in the memory. If the system I / O configuration is consistent with the original I / O registration table, the verification is passed. Otherwise, it will be prompted later.
After the configuration verification, reset the system timer, and then check whether the system hardware and program memory unit are well connected. If they are well connected, it means that the self-test is passed, and subsequent functions can be performed. If one of the above self tests fails, a prompt signal shall be sent.
2、 CPU prompt of automatic winding film packaging machine
There are two kinds of prompts for the CPU of the automatic winding film packaging machine.
- The CPU of the automatic winding film packaging machine only sends out the prompt signal, but does not stop the operation. For example, there are n I / O units in the original I / O registration table, but during this power on self-test, it is found that the system configuration is less than n I / O units, but the channel number occupied by these I / O units configured in the system is still consistent with that in the I / O table. At this time, the CPU does not stop running, but the alarm indicator on the CPU panel is on.
- The CPU of the full-automatic wrapping film packaging machine stopped running, waiting for the user to repair the fault. For example, during the power on self-test, it is found that the channel number occupied by the 1 / O unit configured by the system is not consistent with the original I / O registration table, or the input unit and output unit are interchanged. At this time, the CPU will stop performing the follow-up functions, prohibit the output, and the error indicator on the CPU panel will be on until the user removes the fault.
After the CPU completes the self-test, it carries out the link service and establishes the link with the remote I / O, host or other networked PC. of course, this work is only carried out when the remote I / O unit and the link unit have been configured in the system. Otherwise, go directly to the next execution peripheral command. At this time, the CPU scans the keyboard input of the programmer or other programming equipment, reads and executes peripheral commands, displays the status, compiles user programs and other functions related to the programmer. So far, the preparatory work has been completed. Next, the user program should be executed. Before executing the program, reset the system timer and program address counter to address and record the execution time of the program.
3、 Features of CPU in automatic winding film packaging machine
When the CPU executes the user program, it starts from the vertical bus on the left side of the ladder from top to bottom, scans each element of each step from left to right, and performs the operation. At this time, the CPU only exchanges data with the image area, reads the input data, and sends out the output signal. When the CPU executes the end instruction, it means the end of the program section, then the scanning user program is finished, and then I / O operation is executed. At this time, data is exchanged with the external I / O equipment, the input signal status is read from the terminal of the input unit and the input part of the image area is refreshed, and the output signal stored in the output part of the image area is output to the terminal of the output unit to control the user equipment. At this point, the scanning of the CPU is all over, and the CPU scans and traces these six items repeatedly. The time of each execution is called the scanning cycle. The system program sets the system scanning time to 130ms. When the user’s system scanning cycle is greater than 130ms, the system prompts. However, users can modify the system scan time setting with instructions to adapt to the system with more I / O points.
The CPU is the core part of the whole operating system. To master some knowledge about the CPU in daily operation can avoid the failure of the automatic wrapping machine caused by improper operation!
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