SM331 2AI - problem reading analog input

[Renato 0]

Hello everybody I'm working on a project (on site) using SM331 2AI board (6ES7 331-7KB02-0AB0). Describing the hardware, the SM331 is connected on a remote module IM153-2 that is connected by profibus to a S7-400H through a Y-Link device. I have no errors (SF LED). On the analog input it is connected a ultrasonic sensor with separated power supply and according Siemens manuals it is a 4 wire connection, so the SM331 is configured for a 4 wire 4..20mA connection (on step7 and on the board shunts). I already measured the current with a multimeter, and the analog signal arriving to the board is correct and according the ultrasonic measurements and on S7-400 I'm always reading -32768. Electrically, the board is wired according the attached file. On this equipment (where the remote is mounted) there is no "functional ground" so the terminals 3, 5, 10 and 11 are connected to 0VDC. As I'm using only channel 0, terminal 4 and 5 are shunted. On the step7 hardware configuration, the parameters are as the attached image. Does any one have some ideia about to solve this problem Thanks for your help Best regards, Renato. SM331_2AI.pdf

[JesperMP 2]

Hi Renato. You have 24V+ on terminal 1, and 0V on terminal 20 ? And the measuring range module is in position "D" ?

[Renato 0]

Hi JesperMP I confirm that I have 24VDC on terminal 1 and 0VDC on terminal 20. I also confirm that the shunts (on the board side) are in position "D". Edited 27 Nov 2007 by Renato

[JesperMP 2]

Hi again Renato. The measuring range module must be in position "C" for a 4-wire transducer. To troubleshoot, what are you looking at ? An IW adress or a PIW adress ? If you are looking at the IW, is the address within the PLCs Proces Image ?

[Renato 0]

Hello Jesper In fact the measuring range mudule was already on position "C" and not on "D". For troubleshoot I´m using the module information diagnostic buffer of the analog board and there is no faults or warning displayed. To read the value I´m using PIW528 (I Address for this module on hardware configuration 528...531). Regards, Renato.

[Renato 0]

Hello again Jesper Problem solved ... polarity was inverted!!! Thanks for your help. Best regards, Renato