Siemens S7-1200 / SM 1231 AI4 scaling

dginbuffalo · Jul 2, 2019

Hello- 1st off - I don't get involved with many Siemens PLC's here

I have a 231-4HD32-0XB0 4 channel analog in and a customer provided program.

The customer used a "limit" function to keep the raw analog in between 5530 and 27648 before he normalizes it.

In the device configuration, he has the modules set up as 4-20mA. If the module was configured as 4-20mA wouldn't the range be 0-27648? Or is the raw always 0-27648 for either 0/20 4/20mA and you compensate by setting your min normalized or scaled value to 5530?

Thanks.

Rob... · Jul 2, 2019

See attached, hope this helps.

cardosocea · Jul 2, 2019

The customer didn't know much about PLC's or someone messed up the configuration of the hardware.

Look here for the range.
https://support.industry.siemens.com/cs/mdm/68329511?c=50589335435&lc=en-WW

dginbuffalo · Jul 2, 2019

Rob... said:
See attached, hope this helps.

Thank you. I've seen this and this is where i get confused. Customer says everything looks fine and he is setup as 4-20mA and begins scaling at 5530 raw. By looking at this table, I would think that he needs to start at zero if he has the module set as 4-20mA.

Rob... · Jul 2, 2019

What is the transmitter to the AI card doing?

Does that have some form of internal scaling that means 4mA isn't possible.

dginbuffalo · Jul 2, 2019

Rob... said:
What is the transmitter to the AI card doing?

Does that have some form of internal scaling that means 4mA isn't possible.

They are having trouble with one temperature reading being off. It comes from a temp transmitter in the head of an RTD. It should be scaled 4-20mA = 0-400F. After I open the program and see how all the analogs are set up, I question how they are all working.

dginbuffalo · Jul 2, 2019

This document I found online only shows 0-20mA for that module. Is it possible that in order to use 4-20mA you have to start your scaling at 5530 raw?

cardosocea · Jul 2, 2019

Is that document for the module you listed? It doesn't match what me or Rob... listed.

dginbuffalo · Jul 2, 2019

cardosocea said:
Is that document for the module you listed? It doesn't match what me or Rob... listed.

It may not be.

I think the mystery is solved though. The customer confirmed that the input setup is actually 0-20mA. This makes 4mA approx 5530 raw and this is where his scaling starts. He may just have a transmitter that has not been ranged correctly.

Siemens S7-1200 / SM 1231 AI4 scaling

dginbuffalo

Member

Rob...

Lifetime Supporting Member

cardosocea

Member

dginbuffalo

Member

Rob...

Lifetime Supporting Member

dginbuffalo

Member

dginbuffalo

Member

cardosocea

Member

dginbuffalo

Member

Similar Topics