GX developer: What does UNPAIRED mean?...

[Mas01]

When I do a search of used devices (typically, to find a spare one I can use), this table appears, but I don't understand what "unpaired" means or why ERR appears against some of them.

 

[parky]

Never understood exactly what the Unpaired (ERR) means but that could be Japanese translations are a little bit confusing.
However, it appears that if a variable is used as an output or input without the corresponding in/out then it shows it as unpaired, this would probably be that the variable is used purely to display a value on an HMI or is indirectly addressed.
Not tried it but it is also possible that unpaired could be that setting in an intelligent module i.e. auto transfer data to D registers may not show up in cross reference as paired.

 

[Mas01]

Thanks for this - the reason I was asking is that on our PLC there's specified ranges for D-registers that are latchable (although the picture doesn't show D's but the same principle applies). The latchable values are retained if PLC power is cycled (for setpoints , for example). I'm running out of these D-registers and was thinking of reusing some of the ERR registers. The latchable are found on 'Q parameter setting/Device tab' on GX developer.

 

[Mas01]

Edit... here's the picture

 

[parky]

Just increase the range if you have spare ones either side of the ones shown, it will need a download of the parameters so you must not be running
or you could use latch 2 range with some spare registers, these are basically the same but cannot be reset or cleared using latch clear command, but then why would you want to reset them.

 

[Mas01]

Just increase the range if you have spare ones either side of the ones shown, it will need a download of the parameters so you must not be running
or you could use latch 2 range with some spare registers, these are basically the same but cannot be reset or cleared using latch clear command, but then why would you want to reset them.

Brilliant, Thanks for this parky.

 

[drbitboy]

it appears that if a variable is used as an output or input without the corresponding in/out then it shows it as unpaired, this would probably be that the variable is used purely to display a value on an HMI or is indirectly addressed.

I've seen this e.g. C compiler warnings: reading a value from a variable where that variable never has a value assigned in the code being compiled; writing a value to a variable where that variable is never used for anything in the code being compiled. So it's a housekeeping thing, telling the coder they may have mis-implemented their model. If values are coming in or going out via another path, e.g. via HMI, or initialized before download, of which the compiler is unaware, then it should not matter.

 

[parky]

@DR: If the variable is a real & it is not initialized then yes it can pose problems, I have seen it, the PLC will stop on error (well sometimes), it shows it as NAN (Not a number) however, initially all the registers seem to be zero when first use after downloading a program & parameters, the compiler will not complain as the variable data is not included in the compile as such, just that it is a variable that resides in the PLC, you have to remember that in Mitsubishi all variables reside as set areas in the PLC memory map so are not generated at compile time with the exception of those used purely as symbolic only to be compatible with IEC format, these in the past cannot be addressed from the HMI as it would not know the address, however, I do believe there is a move towards being able to download the symbolic table so that symbolic addressing in the symbols table contain the actual physical address, Mitsubishi at this time only has fixed tables of memory unlike RSL which was a complete change from the older platforms so being able to directly address symbolic rather than addresses. I believe if Mitsubishi do go the whole hog then this will be a completely new platform.
I have been using Mitsubishi for over 35 years & only seen "NAN" 3 times, once because a D register declared as a real (2 D registers) where the 2nd register was mistakenly used as an integer so it effectively corrupted the real value.
The other times I was unable to find what caused the errors, a simple force to 0.0 or some other real number solved the problem that never occurred again.
In general, this would only happen at first download of program then putting the PLC into run.
Mitsubishi have for some reason try to keep their IDE's compatible across the older & new PLC range, does causes small problem but rather that than having to pay for a number of different IDE's for the different platforms.