Question: 3 flow meters connected in series, with 485 signals taken. Is it possible to achieve?
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Current design: 2 mass type units and 1 external clamping ultrasonic unit, connected in series to the DCS via shielded twisted pair, all using 485 signals. Is it possible to achieve this? I heard that something needs to be added to the DCS? I would appreciate some guidance from the teachers.
For DCS485, a communication card is sufficient for communication; each DCS software has its own specific setup method, so consult the manufacturer or look up relevant information. It is a challenge to figure out how to implement the field instruments; one needs to refer to the instrument’s manual. In a DCS system, one communication port can receive data from three instruments. Determining how to assign different stations to these field instruments is also difficult. The communication addresses should be specified in the instrument’s manual, so it should be easy to handle – just check the manual or consult the manufacturer. In DCS, it’s one table per station; as for the field instruments, they should be referred to as parallel ones. I have only worked on 485 communication for paralleling DCS with multiple motorized devices, and the principle should be the same.
Yes, it’s possible to connect the 3 flow meters in series using 485 wires, set the communication addresses and device numbers, connect them to the DCS system’s communication card, and once the parameters are set, everything will be fine
Yes, it’s best to connect them in parallel, with a 200-ohm load resistor at the terminals
Yes, the instrument IDs must be different
Well, that’s possible; the communication card can be set to read from different addresses, using a hand-in-hand 485 communication.
Master, what is the meaning of doing this?