Mitsbishi GX Developer Issue

[kootni]

Hi, In GX developer, I have M502 is shown as “Rst”. Problem is I need M502 “ON” so that my Y005 will switch on to get machine going.

But the ladder in GX Developer is going in circle, not allowing me to see how M502 will switch on. See attached pictur.

 

[AlfredoQuintero]

There has to be another rung in the program which sets M502. I do not know the meaning of Y005 output in your application. We may need a bit more information about the problem. I wish I could be of more help.

 

[kootni]

GX Developer Issue

Thanks Alfredo.

Y005 is output in Mitsbishi plc which gives output (24v) to start machine clutch.

|Y005|- M502| - |pls M61| - here need to have M502 to be in ON state.


See attached screenshot of programme. How can M502 be switched on when it keeps going in loop. There is no outside interventions

This programme was running ok till suddenly it stopped and started showing negative speed values (SPD) on HMI.

What can we done to rectify this?

 

[JTCat]

Where is the PLS for M502?

 

[kootni]

GX Developer Issue

Where is the PLS for M502?

Not sure what you mean? there is no PLS showing for M502.

 

[parky]

But there is a pulse M10 off M500 so that is resetting M502
I would assume that there is an encoder connected to X0 (C235) As this was working there must be some input or state that is causing it without seeing the whole program it is very difficult to understand what is going on.

 

[AlfredoQuintero]

I was thinking the same as JTCat.
Rung 535 shows that when M10 becomes true M502 is reset [RST M502].
There has to be another part of the program in which M502 is set through a pulse [PLS M502] or set to TRUE otherwise by other means. Otherwise M502 will forever remain FALSE and the logic in rung 503 (and other steps before which depend on M502)will not execute.
If there is no such code in the PLC program, then one possibility is that this M502 is set by some HMI and if there is a problem with the HMI the M052 is never set to TRUE and you see the behaviour you describe, and the machine does not start.

 

[kootni]

GX Developer Issue

@Parky

yes there is encoder connected to X0. But why is Y005 not switching on to give 24v to clutch to come on.

Please see attached ladder programme.
Would really appreciate your help.

 

[JTCat]

M502 has to be a field device in a maintained state. Likely from a HMI or other operator interface as previously suggested. M502 will not come on through the program according to your PDF. But it is turned off when a series of events occur.

Y005 will not some on because it is missing the conditional statement M501.

The question we need answered is What are M501 and M502? How are they set if not through the program?

 

[parky]

Kootni, I will look tommorow as busy today to see if I can find out why.
Actually just had a quick look & I looked for KxM5xx which could indicate a batch set or reset etc. of a range of M bits but none found so It does look like this may be set from the HMI or perhaps just been set by the programmer will also look for indicrect address as well.

 

[kootni]

GX Developer Issue

@parky. Cheers.

 

[kootni]

GX Developer Issue

M502 has to be a field device in a maintained state. Likely from a HMI or other operator interface as previously suggested. M502 will not come on through the program according to your PDF. But it is turned off when a series of events occur.

Y005 will not some on because it is missing the conditional statement M501.

The question we need answered is What are M501 and M502? How are they set if not through the program?

HMI is only used to change length in D26 register.

 

[I_Automation]

HMI is only used to change length in D26 register.

Other than the operator HMI, is there a SCADA HMI that is running a recipe control and it sets all the M500+ bits? (and probably some Dword values too as part of the recipe)


This could also be a computer without a monitor or keyboard.

 

[kootni]

GX Developer Issue

Please see attached HMI. Its Mac50.

 

[JTCat]

Do you have MAC Programmer+?