IF logic - Check if Mvar isn't defined in PLC

[shansen]

Is there anyway to check if an Mvar isn't defined within a PLC? Something like:

 

IF(M100-> = *) P100=1 ELSE P100=0 ENDIF

[shansen]

OK, I did end up finding a solution, although I'd still like to hear if anyone has a better way of doing this.

 

To check if an Mvar is defined, I defined a 2nd Mvar that points to the first Mvars' pointer location (see Turbo software reference manual, memory map section). The Turbo PMAC2 Mvars pointers are located at L:$4000-L:$5FFF.

 

M101->X:$4064,24 ;(point to M100 pointer location)
IF(M101>0) P100=1 ELSE P100=0 ENDIF ;(check if M100 is defined or not)

[steve.milici]

This is the best way.