Sign in to follow this  
Followers 0
Guest dtesterman

Mitsubishi A2a

4 posts in this topic

I have a problem that I feel is related to the parameters or other items. When setting a rung to ID my product data, certain internal bits will not "true" although the conditions are correct. Using [= K4 d99]-----(M37)- the bit M37 will not change state. When I change the address to M2, the bit will change when the condition is true. I am trying to find the reason why this occurred, I have searched the Mitsubishi books and I can not find any definitive answer to condition that occurred.

Share this post


Link to post
Share on other sites
[= K4 d99]-----(M37)- The first thing I would look for is M37 being used elswhere in the program. Try moving the line to the last rung before the end statement, if it then goes true, something else was telling m37 to be false after the original statement. This is sometimes not quite so obvious as a double used coil. It might be part of a zone reset (With the A series I think the instruction Fmov is used like zrst) But I would bet that m37 is part of some other instruction.

Share this post


Link to post
Share on other sites
I had already checked to make sure of the double output addressing to make sure that the bit (M37) was not used elsewhere. As far as a Zone reset, I can't find any thing that seems to be tied to it in that way. I am still investigating this myself, even though the issue seems resolved, my program is now working with no issues. I'm just trying to learn the cause. It is always embarressing to be performing a test run and everyone is standing around looking at you when you have these strange problems.

Share this post


Link to post
Share on other sites
I would act in the following order: - check for double coil, - check whether M35 or M36 are specified as destination in CMP or ZCP, - check for zone reset, if M37 is off, - ensure that the rung condition really is true (at the rung execution moment the D99 value may differ from what you are monitoring), - look for shift registers (SFTR/SFTL) that could affect M37, - look for indexed destinations in advanced functions that may result in M37. All of the mentioned should be checked below the subj rung. And funny enough- be sure you are monitoring the ladder similar to the one in the PLC. Use Verify function before monitoring. Regards. Edited by Sergei Troizky

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0