Analog 入力がついた MA-X3xx/LAD では、8ch の AI(A/D 変換) を利用可能です。

コネクタピン配置は下記のとおりです。

sysfs IIO 経由でアクセスします。

root@metis:/sys/bus/iio/devices/iio:device0# ls -l
total 0
drwxr-xr-x 2 root root    0 Apr 28 11:26 buffer
drwxr-xr-x 2 root root    0 Apr 28 11:26 buffer0
-r--r--r-- 1 root root 4096 Apr 28 11:26 dev
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage0_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage0_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage0_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage1_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage1_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage1_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage2_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage2_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage2_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage3_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage3_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage3_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage4_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage4_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage4_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage5_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage5_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage5_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage6_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage6_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage6_scale
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage7_offset
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage7_raw
-rw-r--r-- 1 root root 4096 Apr 28 11:26 in_voltage7_scale
-r--r--r-- 1 root root 4096 Apr 28 11:26 in_voltage_offset_available
-r--r--r-- 1 root root 4096 Apr 28 11:26 in_voltage_scale_available
-r--r--r-- 1 root root 4096 Apr 28 11:26 name
lrwxrwxrwx 1 root root    0 Apr 28 11:26 of_node -> ../../../../../../../../firmware/devicetree/base/bus@f4000/spi@20100000/ads8688@0
drwxr-xr-x 2 root root    0 Apr 28 11:26 power
drwxr-xr-x 2 root root    0 Apr 28 11:26 scan_elements
lrwxrwxrwx 1 root root    0 Apr 28 11:26 subsystem -> ../../../../../../../../bus/iio
drwxr-xr-x 2 root root    0 Apr 28 11:26 trigger
-rw-r--r-- 1 root root 4096 Apr 28 09:56 uevent
-r--r--r-- 1 root root 4096 Apr 28 11:26 waiting_for_supplier
root@metis:/sys/bus/iio/devices/iio:device0#

コネクタ横の DIPSW により、入力毎に 下側(電圧モード) / 上側(電流モード) でモードを切り替えます。