Omega ISA- BUS MULTI-FUNCTIONAL BOARD OME-A822PG - Manual (Page 22)

2.4.6 A/D Gain Control Register
(WRITE) Base+9 : A/D Gain Control Register Format
Bit 7
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
X X X X GAIN3 GAIN2 GAIN1 GAIN0
The only difference between the OME-A-822PGL and OME-A-822PGH is the GAIN
control function. The OME-A-822PGL provides gains of 1/2/4/8 and the
OME-A-822PGH provides gains of 1/10/100/1000. The gain control register control the
gain of the A/D input signal. Bipolar/Unipolar will affect the gain factor.
It is important to select the correct gain-control-code according to Bipolar/Unipolar input.
NOTE :
If the gain control code is changed, the hardware needs an extra delay for
the gain settling time. The gain settling time is different for the different gain control codes.
The software driver does not take care the gain settling time, so the user needs to add
the delay . If the application program will run on different machines, the user needs to
implement a machine independent timer. The software driver, A-822_delay(), is designed for
this purpose. If this subroutine is used, then counter2 as described in sec 2.6 is reserved by
the software driver to implement the machine independent timer.
OME-A-822PGL GAIN CONTROL CODE TABLE
BI/UNI Settling Time GAIN Input Range GAIN3 GAIN2 GAIN1 GAIN0
BI 23
us 1 +/- 5V 0 0 0 0
BI 23 us 2 +/- 2.5V 0 0 0 1
BI 25 us 4 +/- 1.25V 0 0 1 0
BI 28 us 8 +/- 0.0625V 0 0 1 1
UNI 23 us 1 0V to 10V 0 1 0 0
UNI 23 us 2 0V to 5V 0 1 0 1
UNI 25 us 4 0V to 2.5V 0 1 1 0
UNI 28 us 8 0V to 1.25V 0 1 1 1
BI 23 us 0.5 +/- 10V 1 0 0 0
BI=Bipolar, UNI=Unipolar, X=don‘t care, N/A=not available
OME-A-822PGL/PGH Hardware Manual ---- 20