Questions regarding the replacement of cards in Siemens S7-300
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Currently, when the DO card of the S7-300 outputs a signal, two DO signals are sent out simultaneously. The program has been checked and appears to be fine; it is now suspected that there is a problem with the D0 card. I would like to try using another card to see if the issue persists. May I ask whether it is necessary to disconnect the PLC’s 24V power supply when replacing the card? Also, does it need to be done for the expansion modules as well? Thank you!
Checking the card isn’t that complicated, right? Disconnect the load at the output terminal and connect a multimeter; transistors operate at 24V, while relays operate at 220V. If the multimeter can detect the corresponding voltage when a signal is output, then there’s no problem with the card. . . .
Currently, one relay is outputting, and the other relay will also output; when checking the program, only one relay is showing output.
These two points should be in a group, connected together, so. . . Try another one
Through the removal procedure, these two addresses can be tested separately to determine if there are any issues. Simply remove the front wiring harness and replace the clip