Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 145)

Chapter 5
5Ć10
+ lead to TP2, Test Point 2
-lead to TERMINAL 8
2. Adjust R67 for a reading of -10.0000V dc.
A/D Offset Error and Gain Error Compensation
Using the following procedure, adjust the A/D comparator offset error to
zero. Measure, record and compensate for the gain error.
1. Remove programming plug E18. Insert it on one pin, only
(electrically floating). This will be referred to as the OUT position.
2. Move the programming plug E13 from the factory configured lower
position to the upper position.
3. Enable the module’s tieback input 1 by loading 4000 hex into word
W02.
4. Monitor the tieback input word at position 066 for the next three
adjustments.
5. Adjust R68 until the tieback input reading is 0001 hex.
6. Slowly adjust R68 by quarter turns until the tieback input reading
just decreased to 0000 hex.
7. Place programming plug E-13 in the OUT position.
8. Connect the DC voltage standard as follows, set to 10.0000V dc.
+lead to middle pin of E13
-lead to TERMINAL 8
9. Carefully adjust the DC voltage standard until the tieback input
reading at 066 just begins to read OFFF hex. Record this value as
full-scale V
AD
.
10. Subtract 10.0000V dc from the full-scale V AD value in step 9.
Record this value as ^ V. It will be positive or negative.