National Instruments SCC-CO20 Using an External Loop Supply

SCC-CO20

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SCC-CO20

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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.

2	SINK	SCC-CO20	SINK
		2
	Load		+
			–
	0–20 mA		0–20 mA
	+		Load
	–
1		1
	ISO GND		ISO GND
		I

a. Nonreferenced load and external voltage supply (two circuits)

SCC-CO20

2	SINK		2	SINK
	Load			+
				–
	0–20 mA			0–20 mA
	+			Load
	–
1			1
	ISO GND			ISO GND
	+	High	I	+	High
	–	CMV		–	CMV

b. Referenced load and external voltage supply (two circuits)

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.

© National Instruments Corporation 7 SCC-CO20 Isolated Current Output Module User Guide