plc chow coil output problem, what is plc coil coil

Yes, too. However, as long as the output of the double coil in the program is not contradictory, although it will be warned during compilation, the program will still execute normally. Avoiding the double-coil output is actually very simple, use an intermediate relay where the original double-coil output is, and then use this intermediate relay to turn on this output.

The landlord said that it should be Mitsubishi PLC.

Dual-coil output is not allowed for normal programming, but it is possible to output double-coil if programmed with stepping.

But stepping isn't just about using set commands.

No, some PLCs allow humcoil output, where the statement that is scanned first is invalid and the statement that is scanned later is valid. The set directive is in no particular order and works in any position.

As long as the double-coil output in the program is not contradictory, although it will warn during compilation, the program will still execute normally.

Let's change the design idea! If there is no conflict between the two trigger conditions, you can drive the coil with either or logic!

Replace the output point twice with an intermediate relay, and then use the intermediate relay to trigger the output point.

To give you an example that is not very appropriate, it turns out to be: ld

outldout you instead. ld

outldout

ldorout that's fine.

In addition, if the programs do not conflict, even the hummer output is fine.

Only the last one of the double coils can be output, you want an output point with two actions, you can write a line of programs according to the conditions of each action, use an intermediate relay to temporarily store the results, and then use the normally open contacts of these two intermediate relays in parallel as a condition to drive the output point at the back of the program.

A double coil is a coil of the same component that is used two or more times during programming, which is called a double coil.

When a programmable logic controller is put into operation, its working process is generally divided into three stages, namely input sampling, user program execution and output refresh. The completion of these three phases is called a scan cycle. Throughout the operation, the PLC's CPU repeats the above three phases at a certain scan speed.

During the input sampling phase, the PLC reads all input states and data sequentially in a scanned manner and stores them in the corresponding cells in the IO image. After the input sampling is completed, it is transferred to the user hood mining program execution and output refresh phase.

In both phases, even if the input state and data change, the state and data of the corresponding unit in the IO image area will not change. Therefore, if the input is a pulsed signal, the width of the pulse signal must be greater than one scan period to ensure that the input can be read in any case.

In a user program, coils of the same programming element are used two or more times, known as a two-coil output.

PLC dual coil refers to the coil of the same address in the program that has been used 2 times or more.

This is because PLC is a scanning system. If a dual coil is used, then the PLC will take the output of the last coil to appear. As a result, the instructions of the coil that appeared earlier could not be executed.

The solution is generally to adopt the method of excessive intermediate relays, that is, the two-coil local coils use intermediate relays of different addresses. The contacts of these intermediate relays then drive the original coils, avoiding the phenomenon of double coils.

1.All PLC output coils do not have output, and the PLC program is in the "stop state", so set it to make the PLC in the "running state".

The output coil has an output, but the external relay has no output, the power supply is not connected, or the common point is connected incorrectly.

3.A PLC output coil has an output, but an external relay has no output, and the internal physical contact of the PLC output coil may be damaged.

This has been encountered: the PLC is not in the running state, it is like this, set it up, make the PLC "run", and the simulator also has this situation.

The dual coil phenomenon means that the output coils of the same number, for example, appear more than once in the same program, for example. In general, such a phenomenon cannot occur in the same program. The main reason is that when the PLC is scanning the program, the command of the relay output coil may be different, resulting in operation errors, which brings unnecessary economic losses to automated production.

However, in some cases, a dual coil output is permitted.

Dual coil output under the same trigger conditions.

For example, in a program, if the rungs of the same timer are repeated several times in the same program in order to meet the requirements of timing and scanning, in order to make the timer update in time, it is allowed to use the timer coil more than once in the same program. Similarly, the command to update the input and output sample values allows for dual coils.

Dual coil output for reset and set commands.

Because in some programmable controller products, there are two instructions for the coil of a holding relay, one is a reset instruction, which is used to reset or lose the relay, and the other is an set instruction, which is used to set or excite the relay. So at this moment, there are two coils in the program, and if the conditions allow this, it means that the relay coil has two inputs.

Dual-coil outputs that do not affect each other.

In the PLC branch selection program, if one relay coil output is performed in one selected subroutine, the same relay coil is allowed in another selection subroutine. Therefore, as long as one subroutine of the PLC is executed, then the output of the dual coils does not affect each other.

In the control system depicted in the function chart diagram of the PLC, the program is to determine whether the commands and actions of the step are executed by the activity or inactivity of the step. So in different steps, the same relay output coil is allowed. The reason for this is that these relay output coils only function when they become active at a certain step.

It can be seen that under normal circumstances, repeated output of the same coil in the same line should be avoided, that is, the phenomenon of double coil output. In general, the previous coil output is invalid, and only the last output is valid, but in some special cases, double coils appear.

When there are two or more coils with the same name in the program (the same scanning cycle), the execution result of the coil behind the program will cover the previous execution result, which is called a two-wire forest quiet circle conflict.

Note: PLC programs are physically output based on the final execution result.

In PLC programming, we must avoid the problem of double coils.