CONTREX CX-1200 - Manual (Page 86)

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ANALOG CALIBRATION
The Analog Calibration allows you to calibrate the auxiliary Analog I/O, AI1, AI2, AO. The board is
calibrated at the factory and the accuracy should be adequate for most applications. However, you may need
to re-calibrate if your application demands more accuracy in a specific range or if you need to calibrate
directly to EU with a known signal level on the inputs. The Analog Calibration screen is accessed through
Main Menu/Device Tests/Aux Analog Tests/pg 3.
Analog Output (voltage):
1. Connect a voltmeter between pins 10 and 11 with the positive lead on pin 10 (pin 11 is
common).
2. Set AO Mode (CP-291) to “Volts” (1).
3. Set Analog Cal Sel (CP-461) to AO (3) to Select AO for calibration.
4. Set Analog Cal Ref (CP-462) to “A” (1) to select point A.
NOTE: The old calibration data will be overwritten.
5. Set Analog Cal EN (CP-460) to “On” (1) to start calibration.
6. Adjust AO Bit Set (CP-464) until the meter reads the voltage that you want set for point A.
This is generally your smallest (or negative) voltage point. A -12 volts requires about -29500
bits, -10 volts about -24500 bits, 0 volts about 0 bits. For -12 volts, start with about -29400
and use the incremental scroll key .
7. Enter the exact voltage measured by the meter into AnalogRef Val (CP-463).
8. Set Analog Cal Ref (CP-462) to “B” (2) to select point B.
9. Adjust AO Bit Set (CP-464) until the meter reads the voltage that you want use for point B.
This is usually your largest (or positive) voltage point. A +12 volts requires about 30100 bits,
10 volts about 25100 bits, 0 volts about 0 bits. For 12 volts, start with about 30000 and use
the incremental scroll key.
10. Enter the exact voltage measured by the meter into AnalogRef Val (CP-463).
11. Set Analog Cal EN (CP-460) to “Off” (0) to disable further calibration.