I have two PLCs. PLC1 works on foundation fieldbus philosophy. The PLC2 can communiate in 4-20mA hardwired signals or modbus RS485. I want to monitor some analog signals from PLC2 to PLC1. What is the best possible solution? pls. suggest.

 

I don't know what you mean by foundation fieldbus philosophy but in general configure and provide hardwire connection o/p ports of PLC2 for i/p ports of the PLC1 for the Analog signals which you want to monitor through PLC1.(I suppose both the PLCs are located near by)

 

When you state "PLC1 supports FF technology", do you mean that PLC1 supports FF devices?

If that is the case, and you want to monitor the 4-20 mA signals from PLC2, you may have to use a converter such as IF302 from SMAR.

 

The signals from field transmitters (without FF) shall go to a multiplier in control room. One signal from multiplier shall go to PLC2 where there is no problem. Now second signal of the multiplier (without FF) shall go to DCS (emerson) which works on foundation fieldbus. Pls. suggest if IF302 could be suitable or what is the best suitability.....thanks.

 

Perhaps we have an English problem, but I do not understand your original post, nor your further detail. I think you mean that you have an analog multiplexer in your control room that is connected to a PLC. This multiplexer is also connected to an Emerson DeltaV DCS controller. Some other field instruments that use Foundation Fieldbus H1 are also connected to this DCS. This is a normal way to connect legacy field instruments to a DCS.

Emerson DeltaV controllers may have 4-20ma analog input cards installed directly if there are just a few 4-20ma signals, Emerson makes its own multiplexer, or you may choose to use a third party multiplexer (Moore Industries and MTL both make analog and HART multiplexers), both connecting to a DCS via a Modbus link. The SMAR IF302 is a good solution if you want to ADD Foundation Fieldbus capability to a single 4-20ma analog input point to put it on a Foundation Fieldbus H1 segment.

Now, what is your question?

Dick Caro

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