Hello. I am controlling a Frequency convertor(Simovert Masterdrives Vector control) using 1215C Cpu and ET200SP. Analog inputs are connected to AI 8xI 2-/4-wire BA. I connected the wires according to the manual of the module, but the values tha I am reading is wierd. when the motor is not running it is roughly -4500 and when it's running -3800. channels are also set to 4-20mA. 

Attached there are the wiring and setting that I did. 

Thank you in advance.

Hi,

I am not sure if i saw this correctly. But it looks like the converter analog output is an 0-20mA.
If you configure your analog input for 4-20mA this will result in a negativ value if the converter is not moving (0mA from converter, but 4mA expected).
Furthermore this will effect the complete charactersitic curve of the analog loop.

regards

sancruz

Thank you very much. It kind of solved the problem. I am not getting negative values. But now when the motor is not running the values are around 300. The application also needs really small RPM (10 to 20 RPM) which can not be seen in this situation. 

Thank you in advance.

Hello, 

yes, they are in twisted pair cable. 

updates about the procedure that I did. In the manual of the Siemens AG 6SE7087-6JD60 SIMOVERT MASTERDRIVES it's written it can be controlled either via 0-20mA or -+10V. For the analog output of my module (AQ 4xU/I ST ET200SP), I set it to 0-20mA but it didn't work at all, afterward, I changed it to 4-20mA and it worked which was pretty strange why it didn't work with 0-20mA. 

For the analog input (AI 8xI 2-/4-wire BA, ET200SP), I tried 2-wire and 4-wire connections but none of them gave me the right value.  

Attached you'll find the wiring and manual also. I really appreciate if someone can help me.