Basic PLC programming steps for industrial robots

The scientific PLC programming process is actually very simple, but often most engineers think it is simple and neglect many details. Negligence in details will inevitably lead to problems in the future. If you want to avoid future problems, you can only abide by the rules well, no rules are not a circle, PLC programming has its own rules.

Basic PLC programming steps for industrial robots

Basic PLC programming steps for industrial robots

Step 1: Read the product manual

The first step may seem simple, but many engineers can't.

Carefully reading the manual is the first step in programming, first of all, read the safety rules, know which performance agencies may cause personal injury, which institutions are most prone to collisions, and how to solve the most fatal problems when risks arise, these most fatal problems are in the safety rules, reading the product manual is essential.

In addition, the characteristics, application methods, and debugging methods of each component of the equipment are also in the manual, and even if the program is correct, if the components are not debugged well, the equipment will not work. In addition, all the circuit diagrams, pneumatic and hydraulic circuit diagrams, and assembly drawings are also in the manual, and you need to read it to know what kind of modification can be done for each component.

Step 2: Check the I/O according to the manual

View I/O, commonly known as "dotting". There are many ways to check I/O, but you must check it in turn according to the address provided in the manual, and check it when it is safe to do so.

When looking at the input point, the general input signal is nothing more than a variety of sensors, such as capacitive, inductive, photoelectric, piezoresistive, ultrasonic, magnetic, and travel switches. Viewing these components is as simple as placing the workpiece on the station according to the component instructions or moving the fulfillment mechanism to see if the sensor has a signal. Of course, different devices may have different detection methods, depending on the situation.

However, you need to be extra careful when looking at the output signal. In the case of electric drive products, it is necessary to electrify the driver of the fulfillment mechanism under safe conditions, especially under the premise of ensuring that the equipment will not be impacted, and check whether the fulfillment mechanism can move. In the case of hydraulic or pneumatic actuators, the reversing valve is also manually energized to operate the actuator under safe conditions. When looking at the output signal, no matter what the driving method of the fulfillment mechanism is, it must be based on the component manual, first of all, to ensure the safety of the equipment and personnel, and it should be noted that not all the fulfillment mechanism of the equipment can be powered on for testing, so sometimes a single output signal may not be able to be tested manually.

Whether it is an input or output device, when the sensor has a signal or the driving device of the actuation mechanism is energized, it is necessary to check together whether the I/O module indicator light on the PLC is also lit. In many equipment, the input and output signals are connected with the PLC through the terminal block, and sometimes the indicator light of the terminal has a signal, but it cannot be guaranteed that the corresponding address on the PLC is not connected due to the internal circuit of the connecting wire. This is something to keep in mind.

After measuring the input and output signals, the measured address should be recorded together to ensure that the signal address is consistent with the manual. If there is a difference, measure the address of the equipment again, and the measurement is still inconsistent after multiple measurements, contact the equipment manufacturer first, because there is no guarantee that the address provided by the manufacturer is not wrong at this time.

Step 3: Open the programming software, set up the hardware, and write the I/O address in the symbol table.

Different PLCs use different programming software. However, for any kind of software, the first step before programming is to carry out hardware configuration, and establish hardware equipment and corresponding communication equipment according to the type of actual PLC. After the hardware configuration is completed, the I/O addresses that were previously recorded on paper are written down in the symbol table of the software. The definition of the symbol table may be different depending on the software, but it is important for general software to have this function. When writing the symbol table, it is not only necessary to write the positive address of the device input and output correctly, but it is also better to name each address and add comments, which will be very convenient for later programming. You don't need to look up a positive address every time you are programming, you just need to fill in the named title. Of course, it also depends on whether the software has this function or not.

Step 4: Write out the program flowchart

Before programming, it is necessary to write a flowchart of the program on a draft. A good program should include the main program, the abort program, the emergency stop program, the reset program and other parts, if the software allows, each program should be written in the form of "block", that is, a program is a block, and finally each block can be called according to the demand.

PLC is best at processing sequence control, in the order control of the main process is the core, must ensure that the process is correct, to carefully check on the draft. If there is a problem with the main process, when the program is performed by the PLC, it is likely to cause bumps, damage to equipment or pose a risk to people.

Step 5: Write a program in the software

Once you've made sure that there are no problems with the main process, it's time to write the program in the software. In addition, it is necessary to pay attention to the correctness of the abort, emergency stop and reset procedures, especially the suspension and emergency stop procedures, which are the most important procedures related to personal safety and equipment safety, and should not be underestimated. It is necessary to ensure that in any case, only the abort or emergency stop procedure is carried out, and the equipment will not cause injury to people. It is recommended that you pay attention to the training of WeChat signal technology.

Step 6: Debug the program

In this step of debugging, it can be divided into two aspects.

1. If the conditions allow, or your logic is super strong, you can use the simulation function of the software as a test first, but many cumbersome programs are difficult to use software simulation to see whether the program is correct.

2. Transfer the program to the PLC for online debugging. If the equipment does not move or there is an abnormal situation in operation, do not correct the program first, it is likely that the sensor is not debugged in place, if the sensor is guaranteed to be correct, then correct the program.

Step 7: After debugging, correct the program again

In the previous debugging step, since the program was corrected, it is necessary to review or correct the program again, and then transfer the final program to the PLC.

Step 8: Save the program

In this step, it is important to keep in mind the question of where should I save the program? PC hard drive? Flash memory devices? Portable hard drives? Of course, none of these can be infected, all of these storage devices can be infected with viruses. Therefore, it is necessary and only possible to burn the program to the disc. And there is also a question, which program is the program for firing? Previously, we downloaded the program that was finally debugged and corrected to the PLC, and if the PLC performed the program correctly, we uploaded the program to the PC and burned the program to a CD. Everything above is for safety.

Step 9: Fill in the statement

After the programming, you should fill in the final debugging statement, and record the problems encountered and some difficult problems of the program one by one. In the long run, you will also forget about some of the techniques of the program, so that other partners can understand the program you have written.

Basic PLC programming steps for industrial robots

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