Set-Reset Function in Mitsubishi FX2N

Dear All PLC Experts,

During program modification in Mitsubishi FX2N PLC I am facing with some strange problem.

I am trying to set M32 and M33 by M256 and M286 respectively, after Y41 on both (M32, M33) should reset. But during running only M32 getting reset. I am not getting reason for why M33 not gets reset (Please refer image below).

Is it due to scan time?

Is it due to M32 and M33 derived (triggered by Y41)?

Expecting guidance from experts.

Thanks in advance.

Riyaz

There are many possibilities; here are a few

The m33 is double coiled and is being SET again further down the program

M33 is part of a compare statement and the compare is true

m286 is being turned on (if only for one scan) and setting it again

set/reset

hello,

your code is ok. maybe you use M33 in a byte/word? k2M33 ?

hmi

This code looks messy, Not knowing what turns on M256 & 286 I can only guess.
On a scan if M256 & 286 are on both M32 & 33 will be set.
If the rung with M32 & 33 is true Y41 will be turned on & in turn reset M32 & 33.
However if on next scan M256 is off but 286 is on the M32 will be off , M33 will be set again.
This will make the rung with M32 & 33 False so Y41 will be off.
This will not reset M32 or 33 so M33 will stay on.
Why use two relays why not AND M256 & 286 to set M32 only?.
This code looks like there's been a problem & code is just being added willy nilly to try & overcome some bug.

M32 and M33

If M32 resets and M33 does not reset then the M33 Set is on at the same time as the M33. You have to look at whats driving M206

Doug Hylton