Advantech APAX-5013 User Manual page 16

From the figures above, you can choose ID number 0 ~ 15 from the rotary ID switch
("0" ~ "F"). Therefore, the maximum number for analog module in one system is 16.
For digital modules, there is another ID switch on the PCB that it can double the
available ID number. Thus, the maximum number for digital module in one system is
32.
You can distinguish if the ID number is doubled by the front LED. When the LED color
is green, only 0 ~ 15 ID number is used (0 ~ 15 according to the rotary ID switch).
Once the LED color is orange, the ID number is doubled (16~31 according to the
rotary ID switch). Refer to figure below for its location and how to configure it.
APAX-5000 I/O Series User Manual 8