How to properly connec of 2 and 3 wire 4-20ma sensor in cFP-CB-1?

[christensent]

I am connecting 2-wire and 3 wire 4-20ma Sensotec sensors in the cFP-CB-1 with cFP-AI-100 and cFP-AI-110 modules.  There are Voltage and Com connections I am assuming could be used to supply power to the sensor.  There is no voltage on those terminals out of the box. 

What is the proper way to get power?

For 2-wire sensor, I am currently using power supply + terminal to sensor supply + terminal (A terminal for sensotec).  The Output + (D terminal for sensotec) to cFP-CB-1 #6 (channel 3).  Finally, cFP-CB-1 #22 to power supply - terminal.

The setup appears to work fine.  I am getting slightly low readings from the sensor.  I am assuming this is due to the 249 ohm resistor.  What is the acceptable method for accounting for the low readings?

Is there way to configure the CB-1 to supply power to they sensors?

Regards

[Wayne.C]

I personally prefer to use a separate power supply just for the cFP I/O modules.  Otherwise you will have no isolation between your controller module and your instrumentation.

If your readings from the sensor appear low, you may have a problem.  Readings should be very accurate.

Can you give me the model # of sensotec sensor you are using?

[christensent]

My bad, I should've been testing with a newer sensor with current calibrations.

I have tried serveral method to test the signal.  With a Fluke meter providing 4-20, I read 3.995 mA when inputing 4 mA and 19.975 when inputing 20 ma.

I had an older transducer laying around that read 3.965 mA at zero.
Model Z pressure sensor
PN:  Z/7307-3ZG
Range: 20,000 psig
SN: 617676

I have another transducer, much newer reading between 3.995 and 4.000 at zero.
Model Z pressure sensor
PN: 060-7307-01ZG
O/C: AP131EN, 2K
Range: 0-30,000 psig