Issues regarding the signal circuit of Rosemount pressure transmitters
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I connected a separate 24V power supply directly to a Rosemount transmitter, which has a display; the parameters are displayed properly once the transmitter is powered on. However, when I use a 475 device connected in parallel with the transmitter, it keeps showing that no connection can be established. I’m not sure if it’s possible to connect the power supply directly to the transmitter and then to the Hart gauge; normally, it’s a PLC-I/O-transmitter setup, which forms a complete circuit. Could you please advise me on my issue and the reasons behind it?
There is a loop on the back of the case, along with a test connection. Connecting 475 in parallel on the loop circuit enables communication
475 connection, a 250 ohm resistor in series with the instrument circuit
What is the reason for using a 250-ohm resistor?
The Hart handheld can be connected in series with the circuit or in parallel with it. It’s clearly stated in the Rosemount manual
Yes, but can a transmitter and a 24V power supply form a \"complete circuit\" that can be recognized by a Hart handheld device? I tried it, and it couldn’t be recognized. If the complete “circuit” of transmitter-I/O-PLC can be identified.
Check whether your power supply is active or passive; I remember it being passive. I forgot the specifics. Give it a try
The instrument is passive and has only two wires; is the power supply active or passive? Thank you
Power supplies are also divided into active and passive types, and portable power supplies sometimes cannot power smart meters. Also, try connecting resistors in series or in parallel. There are only a few such methods in total; there’s no need to worry about damaging the watch – as long as you don’t make fundamental mistakes, you can give them a try. You didn’t explain your issue clearly either, so I’m just guessing.
Thank you for your patient answer :)