Mux Scan Register -Base+2 - Advantech PCM-3718 Series User Manual

4.4 MUX Scan Register -BASE+2

Read/write register BASE+2 controls multiplexer (MUX) scanning. The
high nibble provides the stop scan channel number, and the low nibble
provides the start scan channel number. The MUX initializes
automatically to the start channel when you write to this register. Each
A/D trigger sets the MUX to the next channel.
With continuous triggering, the MUX will scan from the start channel to
the end channel, and then repeat the process. For example, if the start
channel is 3 and the stop channel is 7, then the scan sequence is 3, 4, 5, 6,
7, 3, 4, 5, 6, 7, 3, 4 ...
BASE+2 (write) - start and stop scan channels
Bit
Value CH3
CH3 to CH0
CL3 to CL0
The MUX scan register low nibble, CL3 to CL0, also acts as a pointer
when you program the A/D input range (see previous section). When you
set the MUX start channel to N, the range code written to the register
BASE+1 is for channel N.
Programming example
This C code sets the range for channel 5 to ±0.625 V:
OUTPORTB (BASE+2, 5); /* SET POINTER TO CHANNEL 5*/
OUTPORTB (BASE+1, 3); /* RANGE CODE FOR ±0.625V*/
Note
PCM-3718 Series User Manual
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D7 D6 D5
CH2 CH1
Stop scan channel number
Start scan channel number
The MUX start/stop channel changes each time
when you change the input range. Do not forget
to reset the MUX start and stop channels to the
correct values after your range setting.
D4 D3 D2
CH0 CL3 CL2
34
D1 D0
CL1 CL0