Instruction manual

PC24E/25E
Page 14
2.5 Enter the data value 4095 which gives a negative full scale output voltage of –2.500 or
–10.000 as selected by J3. Press any key twice to load the DACs.
2.6 Adjust the appropriate trimmer potentiometer to give exactly –2.500V or –10.000V
according to the setting of J3. The potentiometers located at the top of the board are
adjusted according to the table below.
2.7 Select item 3 from the menu. ' Write a value to all four DACs'.
2.8 Enter the data value 0 which gives a positive full scale output voltage of +2.500 or
+10.000 as selected by J3. Press any key twice to load the DACs.
2.9 Adjust the appropriate trimmer potentiometer to give exactly +2.500V or +10.000V
according to the setting of J3. The potentiometers located at the top of the board are
adjusted according to the following table.
Channel
(DAC) Nº
Output
Pin Nº
Trimmer
Negative
Potentiometer
Positive
111RV1RV5
29RV2RV6
37RV7RV9
45RV8RV10
2.10 If any channel will not adjust to the required value over the full span of the
potentiometer, then raise or lower the reference voltage by adjusting RV13 until all channels
can be correctly set up. Repeat the calibration procedure.
2.11 Repeat 2.4 through 2.9 until both ends of the scale are accurately set.
2.12 Enter 0 and confirm to exit the program.
2.5.9 Calibration Check of the PC25E
The PC25E has a single range of 4 to 20mA which is properly calibrated at the factory. This
calibration can be checked if necessary using similar techniques to the above and measuring
the output current with a digital multimeter on a suitable d.c. current range.
Setting a value of 4095 should produce 20mA and setting a value of 0 should produce 4mA.