Discrete Input

Experiencing some problems with AB SLC-5/02. There is one discrete input that when it is actively high, which I can see the green highlight on the PC screen does not pass the logic. When I use the force on this input through the PC it works fine. When I remove the force and go back to standard run mode I have the same problem.

Thanks

Guest

Xref the input and the input word.
Example:
Input I:1/5 and input word I:1.
Also look for indexed addressing (Xref S:24).

The input can have gone bad. That is, the signal activates the LED but it doesnt activate the input logic.

I'll second what Jesper said - XREF and see what else is affecting that input (or the output that your "input logic" is controlling).

Marc

Is that sub-routine being scanned?

Drewcrew6

The input is some type of photo coupler. The led indicating the input is active is on the input side, unfortunately. If the input is correctly addressed, you might try swapping the module with another one to see if the problem follows the module.

Guest,

I experienced the same problem that you had about 5 months ago. I found that the sub-routine was not scanned since I forgot to add the JSR instruction in my PLC program. Try checking this one.

Good luck!

Greetings guest,

When I use the force on this input through the PC it works fine.

Click to expand...

I assume that by "it works fine" you mean that the output actually comes on ... if so, then this seems to indicate that your problem is not being caused by a "subroutine not being scanned" situation ... because ... if the subroutine were NOT being scanned, then simply forcing the input "true" (specifically forcing the INput - not the OUTput) would still not activate the output ...

if all else fails, you might consider posting your .RSS file ... we'll be glad to take a look at it ... you'll probably have to register on the forum before posting a file ... but that's something that you should do anyway ...