Siemens 400 system issues
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After the system is powered off and restarted, 1: Some process alarm values have changed. Can they be restored to their original values? 2: There is also a situation where the display on the central control unit for the solenoid valve does not match the actual status (the central control unit shows it as closed while it is actually open). How should this be dealt with?
1. After a power outage and restart, the process alarm values change. If you make temporary modifications on the screen, they will be reset after a power outage. You need to make the changes in the program and then load them into the CPU, so that the changes are not lost. Temporary modifications can also be made on WICC, but they will revert to their original values once power is lost. 2. Solenoid valves do not provide feedback; what you’re seeing is the feedback of the valve itself. On the screen, if it’s a solenoid valve, the command that should be displayed is related to the operation of the solenoid valve – i.e., it should indicate that the valve is open, yet the indication shows it as closed. In this case, the valve in question is an FO valve, and your description isn’t clear enough.
1. It can be modified back; seek help from a professional. 2. It’s likely that the wires are connected incorrectly; are the actions of the other valve positions also reversed?
1. It is necessary to download various alarm values; if Setp7 is used for direct debugging, an upload is required to maintain consistency after the final restart. The second issue is probably not clearly stated; if there’s a discrepancy, it’s necessary to check whether the actual situation matches what’s shown on-site or on the control panel, and then make the necessary corrections.
1. Make good use of download and upload functions; when using setp7 for debugging, it is necessary to upload the final configuration parameters to the host computer, so that everything remains consistent after restart, and the debugging parameters are not lost when the program is downloaded. For the second issue, find the actual status and then change it to the correct display.
The parameters can be modified back through the touch screen. By electromagnetic valve, you must be referring to feedback, right? If the valve feedback is reversed, you can simply adjust the wiring on site. If what is meant is that the command to the solenoid valve is reversed (which is less likely), then you can apply an inversion operation to the DO in Step 7. I’m not sure if this understanding is correct; it’s just for reference
If it is a program downloaded under PCS7, there is an option: Parameter Readback, which should be checked; it saves your PID parameters and alarm values. For regular maintenance, it is necessary to create regular backups of the programs; this way, even if a download fails, you can still find the previous versions and avoid getting frustrated.