Is the wire connected to M compared to PE/Ground 0V when checked with a meter?  Is your power supply bonded to earth/PE? 

eng.ahmedghozlan

hi all i have same problem now and i check supply volatge it is ok in L+ M- i need to solve this problem

Here is something worth trying.

Swap the DI/DQ and AI module locations in the hardware configuration, and physically swap them on the DIN rail.

Now download the hardware configuration to your PLC.  Does the problem stay with the 1st slot (now the DI/DQ) or does it stay with the AI module?

Is there a firmware update available for your AI module?  How about your PLC?

Apply any available firmware updates. 

Make sure your hardware matches the new firmware, like if FW update changes either of the values in the major/minor FW #.s

Firmware #'s are like Major.Minor.patch, or 1.0.2.  If 1 or 0 change in a firmware update, module selection should change as well.  If the 3rd or where the 2 is in the example changes, no need to update the selected module.

eng.ahmedghozlan

hi all i have  problem in anolag card sm1231 Ai 16 bit give supply voltage is missing now and i check supply volatge it is ok in L+ M- i need to solve this problem 

This analog module is considered a spare part.  It could be Siemens did not enable the diagnostics for L+ with a firmware update 

If you order the current module with the -xx32 in the part #, the power supply diagnostics should work as expected.

eng.ahmedghozlan

i make swap and HW IN Program same physical HW