1794-IF4I Connection with 2 Wires Transmitter


Thread Starter


I am using 1794-IF4I to read and power up analyzer transmitter (Model 5081C-HT from Rosemount). The transmitter is 2 wires connected to the card through terminals 4 & 5. The analyzer didn't power up, is the connection is correct? what is the solution?

Bob Peterson

Normally you would wire the 24 volts Plus to the plus terminal on the transmitter, and the minus terminal on the transmitter would be wired to the input on the card. I don't have a wiring diagram handy for the card you are asking about, but no doubt one came with the card.
As Bob says, I think you are missing the loop power supply. Normally we would provide 24 Volts to the loop, read the paragraph on "Power & Load Requirements" in the Rosemount manual.

Note: Since the input module is less than 100 Ohms, if you are configuring the transmitter with a HART communicator, you may need to add some more resistance in series.
The Rosemount 5081C-HT is a 2 wire HART Conductivity transmitter. I requires 24VDC+ on terminal 16 (+ wire) and the 4-20mA return signal is on terminal 15 (- wire). At the 1794-IF4I assuming TB3 termination the (+ wire) will terminate on terminal 37 (24V dc Power) and the (- wire) will terminate on terminal 4 or Iin. A Jumper from terminal 21 (24V dc Common) to terminal 5 or Iin Return will complete the circuit. Terminals 16-33 are 24V dc Common and terminals 34-51 are 24V dc Power.
I have did this and the analyzer working now. thanks for the solution

I just used terminal 38 instead of 37 and terminal 20 instead of 21.

It was helpful.

Thnx again for all useful replies...