2-Wire Current measurement (4-20mA) using SM 331

Dear Ross_A,

You don't need any additional power supplies.
The 7KF02 card can be used to power 2 wire transmitters. So, all you need to do is to connect your transmitters according to the wiring diagramas shown in S7-300 module data manual.
I've attached a single page of this manual which shows how to connect 2 wire transmitters to 7KF02 card.

The RL means you can't connectindicators or recorders with total resistance more than calculated RL.
For example, If the 7KF02 supplies 24 VDC to the transmitter, then according to calculation,RL will have the value of 700 OHM.
So if you have indicator with input resistance of 250 OHM, You can't connect more than 2 indicators in series with the 7Kf02 module and then the RL will equal 525 OHM (7KF02 has input resistance of 25 OHM).


Best regards.