help with sm331 AI fault

[quote user="marcus71"]I am having a problem with an automated line controlled by an S7-300 plc in that the thermocouple (Pt100) will not show on the HMI. all it shows is 0.00 deg C, Ive checked all the cabling and even replaced the the Input module (331 7kf02 0ab0) and had no success. This unit has beenpowered down over the last week and the battery is not working. When i power up the unit and error message shows on the unit that address 4 is in STOP and the position of the thermocouple module is number 4??. I've very little experience with this sytem and any help would be of benefit.
Thanks.

Hi marcus71,

Which type of CPU are you using? (6es7 31.-....-....)

Does the right value appear in the VAT or STEP7-editor?

Is the PT100-value the only value on the HMI that doen't appear to be the right value?

Thanks for the reply, The CPU is a 314 1AE04-0AB0, one of the problems i have is that i dont have any diagnostic software for these units as the were supplied as original equipment, all the other readings appear ok on the HMI, having said that I cannot get the machine to actually run which may be down to this module fault or possible aproblem with the CPU itself. The AI module is new out of the box and the reading to the Pt 100 is correct (measured by a meter). I am beginning to suspect the CPU but am concerned at replacing it just on a guess.

Thanks Marcus

Am I correct when I conclude that you don't have STEP7 programming software?

Is there any SF-led on? On a module or on the CPU?

See also the manual S7-300Automation System Module data for more information. You can find it at this link.

See also the manual S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP at this link.

No I don't have the software and the only fault LED is fot the battery, this is where I have the problem as I have no way of analysing any of the modules or CPU, I am currently swapping out the CPU with one I know works but thanks fot the info and links,
thanks, Marcus

When only the battery led is on I and your system will not go in Run then I think the program memory in the CPU is cleared.

Do you have a backup of the program on e.g. a memory card? If so, you can place the memory card in the CPU and have a power up. If not you can ask your supplier for a memory card with the software.

If you are using a memory card without a battery all settings are lost every time youswitch off the CPU, having placed a battery the RAM is still powered and settings are kept.

To be sure you can add a battery replacement (CPU must be switched on) in the yearly mainenance instructions thendown times are reduced.

Having typed this information I remembered that Siemens has a link for downloading a free version of STEP7 Lite V3.x at this link.

After installing this on your computer or notebook you only need a PC adapter USB (6es7 972-0cb20-0xa0) for programming/monitoring. Now you can make abackup of the software as well.