Logic Testing

[sutton]

Dear all PLC experts,

I am asking anyone could tell me the best and safe way for Logic Testing on my controller? Instead of my current idea of using few selector switches to test the logic, what are other method that i can try?

The Melsec Medoc software that i'm currently using could not run simulation test. so therefore i have to test the controller directly. and since there were two burnt out cases happened earlier on, i need to be extremely careful. thanks.

Sutton

 

[rsdoran]

For me the simplest test is to install it then do the I/O check to verify the inputs and outputs are in the proper place.

Then do tests in stages per se, let part of the code run then add more etc.

I am currently redoing a sealer, the main aspect I wanted to test first was using a timed sequence to maintain the cutting wire at a certain temperature but with no way to monitor the temperature. My main goal was to make it heat but not overheat..ie expand the wire too much.

Another aspect was a form of an antitie down pushbutton sequence to keep operators from holding or tying down one button then pushing the other when they wanted it to run.

There is nothing like using the machine, in some cases it may be necessary to disconnect some things during the test to verify it works as expected.

NOTE: I am not nor claim to be a professional programmer, others here are by far more experienced at this. I can only state from my experience and it hasnt been with large systems or systems that involved in depth safety issues.

I am the guy that installs or services the machines most here design/build.

 

[Goody]

If you upgrade your medoc software to GX-Developer you will find that this has simulation software called LLT (ladder logic test)
You can test most things with this.

 

[nif]

Hello!
Usually if you don't have the inputs you can simulate them with
a PLC by changing the input/output to memory bits.
e.g. I 0.0 -> M 0.0 and so on.
If you know that you have to simulate the input/output you can write the program so that you read all the input to memory places in the beginning of the cycle, and write the memorybits to outputs at the end of the cycle.
e.g. (simatic world)
begining of cycle

A I0.0
= M0.0
..
..
A I100.0
= M100.0

End of cycle
A M200.0
= Q0.0
..
..
A M400.0
= Q100.0

In siemens there are other ways to simulate I/O without having to change the program (software..hardware)