4 – 20 mA Current Loop Connections

Before connecting the current loop, insert the shorting jumper on the board for each channel used to measure current loops. This jumper inserts the 62-ohm shunt resistor across the input of the A/D. If multiple current loops are connected to one board, all must share the same power supply and ground reference points or the accuracy of all the current loops need to be checked for accuracy.  When setting up a current input signal, such as a 4 – 20 mA signal, the jumper must be placed on the pins in the current setup (right diagram).  Notice that there is also a jumper set up in the 1:1 setup only when inputting a current signal.  This is because current signals also have a corresponding voltage signal.

 

Warning: Connecting a mA input without the Input Jumper will damage the input.

 

To add a jumper to an input:

1. Power down the unit.

2. Remove the thermocouple connector and the Ethernet cable from the DAQ.

3. Remove the top plate of the DAQ by unscrewing the screws around the top of the DAQ. 

4. Grasping both sides of the input board, carefully pull the input board out of the DAQ and set the jumper for the appropriate set of pins, i.e. “V1” for input 1, “V2” for input 2, etc. A jumper will need to be set – placed on both pins – to be considered “on”. Slide the input board back into the DAQ slot.

5. Replace the top plate of the DAQ by screwing in the screws around the top of the DAQ.

6. Re-connect the Ethernet cable and thermocouple connector.