Specifications

51
D.2 D/A Calibration
Note:
✎ Using a precision voltmeter to calibrate the D/A outputs is
recommended.
The auto-calibration program AutoCali.EXE helps you finish the D/A
calibration procedure automatically. Although the procedure is not
necessary, the following calibration steps are provided below for your
reference in case you want to implement the calibration yourself:
1. To adjust those eight jumpers JP1~JP8 to 0~20 mA.
2. Setting the output range as ± 10 V for channel 0 (BASE+14H).
3. Adjust offset calibration. First, output 0x8000 to channel 0. Then
writing the value from 0x00 to 0xFF sequentially to BASE+1EH,
and to see whether the output voltage is corrected. If so, to go to
next step. Otherwise, you must change the value and repeat all the
procedure in this step again until the output voltage is corrected.
4. Adjust gain calibration. First, output 0xFFFF to channel 0. Then
writing the value from 0x00 to 0xFF sequentially to BASE+1EH,
and to see whether the output voltage is corrected. If so, to go to
next step. Otherwise, you must change the value and repeat all the
procedure in this step again until the output voltage is corrected.
5. To change to another channel and repeat steps 2 to 4 to calibrate all
eight channels.
Table D-1 D/A binary code table
A/D code Mapping voltage/current
Hex. Dec.
±
±±
± 10 V
0~20 mA 4~20 mA
0000h 0
-FS ± 6 LSB
N/A N/A
8000h 32768
0 V ± 6 LSB
0 mA 4 mA
FFFFh 65535
+FS ± 6 LSB
20 mA 20 mA
Note: 1 LSB = ±FS / 65535 = 20 / 65535