Advantech PCI-1718 Series Carbon Monoxide Alarm User Manual


 
85 Appendix D
D.3 D/A Calibration
Connect a reference voltage within the range ±10 V to the reference input
of the D/A channel you want to calibrate. You can use either the on-board
-5 V (-10 V) reference or an external reference. Adjust the full-scale gain
and zero offset of the D/A channel with VR5 and VR6, respectively. Use
a precision voltmeter to calibrate the D/A output.
Set the D/A data register to 0 and adjust VR6 until the output voltage
equals 0 V.
Set the D/A data to 4095 and adjust VR5 until the D/A output voltage
equals the reference voltage minus 1 LSB, but with the opposite sign, For
example, if V
ref
is -5 V, then V
out
should be +4.9988 V.
Note: Using a precision voltmeter to calibrate the D/A
outputs is recommended.