How to send digital signals to the PLC and then to the DCS
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I would like to ask the experts: how can a switch signal, such as that from a level switch (assuming it has only one pair of contacts), be routed in a system so that one path goes to the PLC while another path goes to the DCS?
It is possible to first go to DCS, and then use logic to convert DI to DO and send it to the PLC.
Experts... there are no experts here; it’s all friends. There are two options. The first is to connect to the DCS as mentioned above first, and then output the signal, connecting it to the PLC via a relay. The second method is to use a relay directly, selecting two output paths: one going to the DCS and the other going to the PLC.
Directly control the relay, and then connect the relay’s contacts to the DCS and PLC respectively
By adding relay contacts, it can be connected arbitrarily
Convert DI to DO in the PLC or DCS and send it to another system, or use the same intermediate relay to generate two signals that are sent separately to the DCS or PLC
Convert DI to DO and send it to another system
A signal distributor with one input and two outputs can be added, or communication can be established after it connects to the DCS or PLC
Using an intermediate relay remains economical and reliable, while also allowing isolation from the field equipment.
The simplest way is to add an intermediate relay, which divides the signal into two streams going to the DCS and the PLC, thereby achieving the desired function.