X20 system modules • Analog input modules • X20AI1744, X20AI1744-3
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X20 system User's Manual 3.10
4.3.2.6 Connection examples
Full-bridge strain gauge with 4-line connection
GND
+24 VDC
GND
+24 VDC
⊥
+
-
AI
Full-bridge strain gauge
+U
Figure 49: Connection example - Full-bridge strain gauge with 4-line connection
Full-bridge strain gauge with 6-line connection
Precision can be improved by using strain gauge cells with feedback of the bridge voltage. The additional sensor
lines with the strain gauge bridge supply compensate for the thermal resistance change of the feed lines. If a 6-
line strain gauge cell is connected to the module, the sense lines are bypassed by the 4 internally linked strain
gauge VCC connections (i.e. strain gauge GND). For this reason, the line compensation no longer functions.
The measurement precision is therefore affected by changes in operating temperature. Longer cable lengths and
smaller cable cross-sections also increase the potential for errors in the measurement system.
In order to reduce cable resistance, the sense lines should be connected in parallel with the strain gauge bridge
supply lines. Optimal signal quality can be obtained by using a shielded twisted pair cable. The connections for the
strain gauge supply lines, the sensor lines, and the bridge differential voltage lines should each use one twisted
pair cable.
GND
+24 VDC
GND
+24 VDC
AI
⊥ ⊥
+
-
Full-bridge strain gauge
+U Sense
+U
Sense
Figure 50: Connection example - Full-bridge strain gauge with 6-line connection
Summary of Contents for X20 System
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