1771 AB I/O module in a remote rack, need help changing the scaling

[Keldog]

I am trying to change the scaling using rslogix5000 and was wondering if there is a way i can do it without shutting down the processor, i am using BTW and BTR's to read and write the information to the processor.

 

[jonesy29847]

Is this an analog module?

Its been a long time since I've used an analog module, but I think there are words in the BTW file that specify scaling. If thats the case my next question becomes what happens when you change the values?

One pecularity of the module was that if you wanted to use scaling you had to specify scaling for all channels even if not used.

 

[Keldog]

When i change the values it goes back to the value that was originally in the tag. It is an analog module sorry for not specifing that in the description. I have BTW files but i can't find them to change them. I was thinking about putting a bit in there to make the BTR read after i made the changes would that make a difference.

 

[jonesy29847]

Could there be something else writing to the tag?

 

[jonesy29847]

I should have associated scaling with analog modules.

 

[Keldog]

I don't think there is, i just am worried about having to go offline with the processor to change the values i'm trying to avoid stopping the processor cause it will cause bigger problems for me in the end.

 

[hillimonster]

Are you trying to change the scaling of a point, meaning 0-10VDC to 4-20mA. Or are you trying to rescale a particular channel so that it reads correctly. I can give you the register locations for the later (based upon PLC5 documentation) and probably for the former as well (just have to look in older documentation).

 

[jonesy29847]

Keldog, are you trying to change values in the BTW file?

If so and they get reset get the cross reference for the particular tag you are using and look at any MOV, COP instructions.

In RS5000 cross reference gets you a better report, it is confined to a single window and indicates what instruction is associated with the address.

Assuming

 

[jonesy29847]

Sorry Keldog,

I can't find the BTW in the CLX instruction set. So can you tell me what instructions are used for the module. Or better yet send me the program.