Allen-Bradley 1794-IRT8, Руководство пользователя

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Publication 1794-6.5.12 - November 1997
6-8 Calibrating Your Module
Current Source Calibration
The current sources can be calibrated one at a time or all at once. To
calibrate the current source for all inputs at once, proceed as follows:
1. Connect a 383 ohm, 0.01% resistor across (H, +) and (L, –) of each
input channel (8 resistors).
2. Apply power to the module for 20 minutes before calibrating.
3. Initiate a BTW to the module with the2401 (hex) value in BTW word
3, bits 00-15, as shown above.
4. Monitor the block transfer read word 10, bits 00-15 for an echo of the
EDT command.
If the BTR word reads 80FF (hex) (indicating a failed calibration), repeat
the BTW. Make sure that sufficient time is allowed for the module to
respond to your request.
5. Connect a 100 ohm, 0.01% resistor across (H, +) and (L, –) of each
input channel (8 resistors). Repeat steps 3 and 4 using a BTW value
of 2402 (hex).
6. When all calibrations are successful, proceed to the “cold junction
calibration.”
Cold Junction Calibration
Both cold junction compensation inputs must be calibrated together. To
calibrate both at once, proceed as follows:
1. Connect a 10 Kohm, 0.5% resistor across terminals 37 and 39 (cjc 1)
and terminals 46 and 48 (cjc 2).
2. Apply power to the module for 20 minutes before calibrating.
3. Initiate a BTW to the module with the 2404 (hex) value in BTW word
3, bits 00-15.
4. Monitor the block transfer read word 10, bits 00-15 for an echo of the
EDT command.
If the BTR word reads 80FF (hex) (indicating a failed calibration), repeat
the BTW. Make sure that sufficient time is allowed for the module to
respond to your request.
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