Rockwell Automation 1771-IR , D17716.5.76 RTD INPUT MODULE User Manual
Page 40
Module Calibration
Chapter 7
7Ć7
is, you want to subtract 47 counts from your input data. The lower byte
remains 00 during offset calibration.
5. Repeat above steps for channels 2 through 6 respectively.
6. Apply the values by sending a BTW to the module.
Gain Calibration
1. Connect the 402.00, .01% resistors to the swing arm as shown in
Figure 7.2.
2. Place the module in platinum ohm mode. This provides 30 mohm
resolution display.
3. Examine word 3 of the read block transfer data file. It should be around
13400 decimal. Your actual value will be a percentage of 13400.
For example, if the data in word 3 is 13408, then:
(13400–13408)/134000 = –0.000597.
Your actual data value differs from the theoretical value (at 402.0 ohms
input resistance) by –0.000597, or –0.0597%.
You can compensate for this error by entering the percentage difference in
binary coded fraction form. Table 7.D lists the value for bits 7–0.
Table 7.D
Value for Bits 7 through 0
Bit
Value
Bit 07
Sign bit
Bit 06
= 0.0976562%
Bit 05
= 0.0488281%
Bit 04
= 0.024414%
Bit 03
= 0.012207%
Bit 02
= 0.00610351%
Bit 01
= 0.00305175%
Bit 00
= 0.00152587%