Problems with the S7-300 AI module
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I currently have an 8-channel AI module; 2 of the signals are of the 4-20MA type, while 6 signals are of the 0-20MA type. Initially, the negative terminals of those 6 0-20MA signals were connected to the negative terminal of 24, and everything was displayed correctly on the WINCC screen. Now, for some reason, the 2 4-20MA signals keep showing the maximum value
First, verify the correctness of those two signals. Next, check for any sources of interference; for example, in the case of 4-wire signals, I short-circuit both the signal negative terminal and the power supply negative terminal. I’ll take another closer look
Reply to 2# faner: All the signals are correct; everything is fine.
1. Check whether the 24V voltage is normal. Then use a multimeter to check whether the current is greater than 20mA or less than 20mA. 2. There are spare parts; try another one. But it’s probably a wiring issue. 3. Check in STEP7 whether there are any fault messages for this module; if so, follow the instructions. 4. The usual connection method is to short-circuit Mama and M. From your description, it seems you have shorted M- (signal-) and M (power-). 5. Measure the voltage between M- and Mama. It feels like the high and low ends are connected together. Finally, call Siemens’ support line at 400-810-4288