National Instruments Isolated Current Output Module SCC-CO20 - Manual (Page 7)

© National Instruments Corporation 7 SCC-CO20 Isolated Current Output Module User Guide
Using an External Loop Supply
In order for the current sink to operate properly with an external loop
supply, the voltage must be within the range of 3 to 42 V. If the voltage is
too high, overheating can occur and damage the module. Figure 4 shows
four configurations using an external loop supply.
Figure 4. Connecting the SCC-CO20 Using an External Loop Supply
When you use an external loop supply, the order of the supply and load does
not matter as long as you do not create a second loop through which current
flows. If both the supply and the load are grounded, connect the signals as
shown in Figure 5.
High
CMV High
CMV
1
2
Load
SINK
+
–
SCC-CO20
ISO GND
I
a. Nonreferenced load and external voltage supply (two circuits)
b. Referenced load and external voltage supply (two circuits)
1
2
Load
SINK
+
–
SCC-CO20
ISO GND
I
1
2
Load
SINK
+
–
SCC-CO20
ISO GND
I
1
2
Load
SINK
+
–
SCC-CO20
ISO GND
I +
–
+
–
0–20 mA 0–20 mA
0–20 mA 0–20 mA