Questions regarding the wiring of three-wire and four-wire systems in the module?
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For the field three-wire system and the module three-wire system, this wiring method is applicable. But why do all the negative wires of the analog module need to be connected in series? Additionally, for the field two-wire system and the module four-wire system, how should they be wired? I’m very confused; could an expert explain it to me? .
I don’t know what system you’re using; different systems require different connection methods
The question is too general; the issue can only be resolved by specifying the model of the DCS system and the IO cards, etc.
What type of signal do you use: three-wire or four-wire? Which manufacturer’s DCS should it be connected to, and what type of card is needed?
Let’s talk about the general situation: there are different models and different card components. I’ll mention a few scenarios; I’m still new to this and don’t understand many things yet. Thank you! !
It’s necessary to check the specific situation; it’s related to both the instruments and the system
It’s a three-wire system on-site, as well as in the modules; this connection method is feasible. But why does the negative wire of the analog module need to be connected in series? How should it be connected? I’m very confused; could an expert explain it to me? . Three-wire type, seems to be used for thermistors; there is an RTD signal module ； I’ve never seen it before; there are four-wire versions of this module, and I’m not sure which manufacturer makes them. It’s really convenient. In the past, four-wire instruments provided an external power supply circuit, with the signal circuit connected to a two-wire passive module – it was really troublesome! (I’m not sure if the four-wire system I mentioned refers to the same thing as what the original poster is talking about?) ) Additionally, the field instruments are two-wire type; why are four-wire modules used instead of two-wire modules?