Issues with instrument power supply~
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Excuse me, does a pressure transmitter require power? It is two-wire system and does not require a separate power supply, but does it actually still receive power from the card module? Or isn’t there even any power to activate the card reader? Looking at the IO list provided by the design institute, the field for power supply of the pressure transmitters wasn’t filled in before; this time it has been filled with “24 VDC, two-wire system”. What does that mean?
Yes, the power cable and the signal cable share two wires.
It is generally powered via a loop, meaning the signal line and the power supply share two wires in a two-wire system. That is, 24V DC connected in series with the signal line
There are generally two types of power supplies for field transmitters: one is an AC 220V power supply, with the power line and the signal line being separate； One type is a 24V DC power supply, which generally uses a two-wire system, meaning that the power supply and the signal share the same pair of wires. A transmitter will not function without power.
Pressure transmitters are usually two-wire systems, powered by a card; electromagnetic flowmeters are typically powered at 220V, and no power is required for the card. This isn’t a problem – there are usually jumpers available for powering the card, and it can be set up easily.
It needs to be powered; passive power supply method
It’s powered by 24V; in a two-wire system, the signal line and the power line are combined into one wire
The two-wire system is based on the use of integrated circuits; in other words, the transmitter consumes very little power and functions properly at 24V and 3mA.