Input Range Selection; Mux Setting - Advantech PCM-3718 Series User Manual

5.2 Input Range Selection

Each A/D channel has its own individual input range, controlled by a
range code stored in the onboard RAM. Please refer to pages 28 and 29
on A/D Range Control, for more information.

5.3 MUX Setting

PCM-3718 cards offer 16 single-ended or eight differential analog input
channels. Set jumper JP2 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 PCM-3718 card for eight
differential input channels, set bits CH3 and CL3 to zero.
The MUX scan register data format is as below:
BASE+2 (write) - start and stop scan channels
Bit
Value CH3
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 chan-
nels, PCM-3718 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 automatically resets to the start channel.
You can specify channel settings by writing directly to the MUX scan
register. Use the MUX scan register to assign to a specified channel
when you set channel input ranges (with BASE+1). After you set the
input range, you will need to reset the MUX register for the proper start
and stop channels.
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D7 D6 D5
CH2 CH1
D4 D3 D2
CH0 CL3 CL2
45
D1 D0
CL1 CL0
Chapter 5