Seeking expert advice on the control logic
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There is a pump on site that has interlock shutdown functionality built into the DCS; the local and remote switch controls for it are also integrated into the DCS, as are the reset buttons. There are start/stop buttons on site, but they are not connected to the DCS. The problem is that if the pump is manually stopped on site, and without any interlocks in the DCS, everything switches to remote control and the pump will start up again. This is not what we want to happen. I’m not sure how to set up the logic to prevent this from occurring. Any advice from those with experience would be greatly appreciated! Thank you!
If I switch to remote, does the pump start? Shouldn’t it be that you need to switch to remote mode first, and then press the remote start button? There is also a makeshift solution: add an emergency stop button on site.
Reset the pump’s control interlock by using an AND operation of the pump’s operating status signal and the local/remote transmission signal
Check whether your remote start function is an open-circuit type or a closed-circuit type. Normally, it should be an open-circuit type; in that case, even when in remote mode, only a pulse signal is sent to start the pump, and the pump will not start as soon as it is switched to remote mode