Dear Masters, why can’t the PA signals of fieldbus equipment directly enter the DCS?
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Why can’t PA signals from fieldbus devices enter DCS directly? It needs to be connected to the DCS through the PA/DP coupler.
Any signal, whether analog or digital, must comply with the signal standards of the DCS itself before it can enter the DCS. For analog signals, it must pass through the analog card. The standard signal is 4~20MA. After entering the card, the card will automatically Replace it with a signal that matches your own. This is why DCS cards from different manufacturers are not universal. The same is true for your fieldbus instruments. Fieldbus types must also enter the DCS through the manufacturer's conversion module. The coupler you mentioned is one type.
No, what system are you using?
The DP/PA coupler is the physical connector between PROFIBUS DP and PROFIBUS PA. It makes it possible to address PA field devices via PROFIBUS DP in stand-alone operation. No other components are required. DP/PA couplers are also used for more advanced coupling tasks in DP/PA connectors. The DP/PA coupler Ex can be used to connect PA field devices in explosion-proof environments.
Yes, yes, I just don’t understand that the PA signal does not enter the system directly through the PA module of the DCS (I don’t know if there is such a module), but is converted by the DP/pa module and then enters the DCS through the DP module of the DCS. Isn’t this an extra conversion?
ABB and Emerson are all like this. They require PA to convert the backward DCS through a coupler.
This answer seems to be quite reliable. I wonder if DCS has a module that can directly process on-site PA signals, reducing one conversion process.