Interlocking between controllers
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I have a question: there are multiple wine storage areas, with each workshop equipped with a PLC control system. It’s possible that the owner may require interlocks between the tanks in one workshop and those in another workshop. Is it possible to achieve this?
Yes, it is possible to transmit interlock signals through the host computer； Or interconnect interlock signals between workshop PLCs.
For critical interlocks, use DI and DO hardwired signals to establish interconnections between various PLC systems; do not rely on communication.
Well, since each PLC is located at a great distance from the others, and as per the owner’s previous requirements, there are too many interconnections in the interlock circuits. The control system manufacturers we consulted earlier said that communication could be used; it would be sufficient to connect all the CPUs together. If this approach isn’t reliable enough, then other methods of interconnection should be considered
For interlocking between control systems, if the manufacturers are different, you will be told that it’s not possible to do so – only hardwired interlocking can be used. It would be easier if it were one company, as manufacturers are concerned about system compatibility issues and coordination with competing companies. Theoretically, it can be done as long as the address of the DI signal that needs interlocking in the PLC is identified. It is better to use a field bus rather than communication, as the latter may result in data loss. With hardwiring, it is possible to run wires directly from the DI card that requires interlocking to the DI card of another system, which is less complicated than using fieldbuses.