S7-200 and analog input problem

[mniknezhadi]

Dear everybody

Please guide me about analog input problem in siemens s7-200. I use two type of analog input modules, the spec. of first one is:

EM 231

AI 4x 12 Bit

231-0HC32

And the 2’nd one is:

EM 231

AI 8x16 Bit

231-0Hf22-0XA0

The first one is operates normal, but the second one dose not do anything. I replaced the 2’nd one instead of 4 input analog module to test but it doesn’t do anything again.

I have set the dip-switches as follow:

For 4 input analog module:

Dip 1 and 3 are on as siemens manual for 0-10V input.

For 8 input analog module:

Dip 3 and 5 are on as siemens manual for 0-10V input.

For more information I have checked the SMB8 and SMB9,they were as SMB8 =12(00001100) and SMB9= 0.

I would be pleased if someone write me for more help and guidance.

[BryanG]

First obvious question, is the power indicator on the module lit. If not it is either a supply problem or a sensor is shorted to ground.

Bryan

[mniknezhadi]

Dear BryanG,
Yes the power indicator is lit. In adition I have checked the sensors and wiring. As I wrote I replaced an other module with 4 inputs instead of 8 inputs module and it works well.

[BryanG]

Next step, which you will probably have done is to connect a meter across the 10V input and make sure that there is a signal there and that it is the correct polarity. If that is OK then there are two possibilities:
A faulty Analogue Unit.
Siemens haven't made the new 8 input analogue unit backwards compatible with older PLC firmware versions.

Either problem will need a call to your local Siemens Technical Support or post a question on the Siemens Forum.

Bryan