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Chapter 5
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:
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.
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
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