Rockwell Automation 1794-IRT8XT FLEX I/O Thermocouple/RTD /Millivolt Input Module User Manual - Manual (Page 59)

Publication 1794-6.5.12 - September 2011
Calibrate Your Module 47
2. Apply power to the module for 20 minutes before calibrating.
3. After the connections stabilize, initiate a write word with the appropriate
EDT command location (write word 3, bits 00…15) as shown above.
4. Monitor the value in the EDT response location (read word 11,
bits 00…15) for an echo of the EDT command. Depending on which
command you sent, it should show 242X Hex.
If the EDT response word reads 80FF (hex), repeat step 3. Make sure to
allow for sufficient time for the module to respond to your request. If
there is no change, calibration has failed. Check the wiring and try again.
5. Set the precision millivolt source to the value required for a gain of 2.
Repeat steps 3 and 4 for gain 2. Repeat for each gain setting.
When all gain calibrations are successful, proceed to perform Current Source
Calibration on page 47.
Current Source Calibration
The current sources can be calibrated one at a time or all at once. To calibrate
all the current sources, proceed as follows:
1. Connect a 383 Ω , 0.01% resistor across (H, +) and (L, -) of each input
channel (8 resistors).
2. Apply power to the module for 20 minutes before calibrating.
EDT Commands for Gain Calibration
All Channels Single Channel
EDT Command EDT
Command
Dec. or Hex
Bits 8
…
15
EDT Command
Data
Dec. or Hex
Gain
Selected Input (mV) Hex Decimal Bits
4
… 7
Bits
0
… 3
1 -320.00 + 0.064 mV 2420 9248 06 0 … 7 0
2 320.00 + 0.032 mV 2421 9249 06 0 … 7 1
4 110 + 0.016 mV 2422 9250 06 0 … 7 2
8 70.00 + 0.008 mV 2423 9251 06 0 … 7 3
16 29.00 + 0.004 mV 2424 9252 06 0 … 7 4
32 19.00 + 0.002 mV 2425 9253 06 0 … 7 5