WinSystems PCM-AIO, Operation Manual, Page: 13 / 43

same data to the I/O port BASE+0. This mode is made avail able so that a vari able time can
be in serted be tween write cy cles to al low the Track/Hold cir cuit to ac quire the in put sig nal.
2.11
A/D CALIBRATION PROCEDURE
The PCM- AIO is cali brated at the fac tory for the 0-5V range of op era tion. When switch -
ing to an other in put range, a slight ad just ment may be nec es sary. The fol low ing pro ce dure
is given to cali brate the PCM- AIO for any in put range.
2.11.1
CALIBRATION PROCEDURE
1. Se lect the de sired mode and in put volt age range. Use a soft ware rou tine that will loop
con tinu ously on one chan nel.
2. OFF SET/ZERO AD JUST MENT. (TRIM POT R3)
Ap ply a volt age source be tween the se lected ana log chan nel and ground. A 1uF ce ramic
ca paci tor should be used across the in puts to sup press noise. Ad just the out put of the volt -
age source to +1/2 LSB. Ad just the off set/zero trim ming po ten ti ome ter R3 so that the out -
put code flick ers equally be tween 000 HEX and 001 HEX for uni po lar op era tion and 800
HEX and 801 HEX for the bi po lar mode.
3. FULL SCALE AD JUST MENT. (TRIM POT R2)
Change the out put of the volt age source for +FS-1 1/2 LSB. Ad just the gain trim ming
po ten ti ome ter R2 so that the out put code flick ers equally be tween FFE HEX and FFF
HEX.
980723 OPERATIONS MANUAL PCM-AIO Page 2-5
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