Advantech PCL-818L, User Manual

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Chapter 5 A/D conversion 39
Bits in this register indicate the end of conversion status, single-
ended/differential input, interrupt status and the number of the
channel to be converted next. Refer to Chapter 4, A/D status register,
for more information.
Input range selection
Each A/D channel has its own individual input range, controlled by a
range code stored in on-board RAM and the setting of jumper JP7.
Please refer to Chapter 4, A/D range control, for more information.
MUX setting
The PCL-818L offers 16 single-ended or eight differential analog
input channels. Set jumper JP6 for the channel configuration before
you set the multiplexer scan range. The MUX scan register specifies
the high and low limits of the scan range. The MUX scan register is a
read/write register at address BASE+2. Bits D0 to D3 hold the
starting channel number, and positions D4 to D7 hold the stop scan
channel number. When you set the PCL-818L for eight differential
input channels, bits CH3 and CL3 must be zero.
The MUX scan register data format is:
BASE+2 (write) – start and stop scan channels
Bit D7 D6 D5 D4 D3 D2 D1 D0
Value CH3 CH2 CH1 CH0 CL3 CL2 CL1 CL0
If you require only one A/D input channel, you should set the high
and low scan limits to the same value. If you specify a range of input
channels, the PCL-818L automatically performs an A/D conversion
on each channel in the range, beginning with the start channel. When
it reaches the stop channel, it loops back to the start channel and
continues. This looping continues until the specified number of
conversions is completed. Note that writing to the MUX automatical-
ly resets it to the start channel.