Mitsubishi: what does M stand for in a parameter?

Mas01

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• Oct 28, 2020

• #1

I've got a bunch of alarms in GT designer3 and they are "mapped" to M parameters, eg M277. What does M signify? Thanks

 

parky

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• Oct 28, 2020

• #2

M is a memory bit or flag.
The PLC contains X (Inputs) Y (outputs) M bit memory, D Word memory R word memory, Timers & counters

 

AlfredoQuintero

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• Oct 28, 2020

• #3

In addition, some of the bits in the M tables are system bits. Things like ALWAYS_ON, ALWAYS_OFF and first scan bits. You need to check the Mitsubishi documentation.

 

Mas01

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• Oct 28, 2020

• #4

Many thanks, chaps. Another piece of the puzzle sorted.

 

parky

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• Oct 28, 2020

• #5

As posted above, the system bits (depending on the PLC Model) are M8000 > for FX, SM0-xxx for the Q series, although I believe there is some cross over, M bits 9000 > are used for the GXIEC/GXWorks as temporary or local variables at compile time.