ILS ILS22GS win7/8 - Manual (Page 4)

Backlight controller.
When the ILS22 is delivered in a standard setup, an internal PC is used to control the system
and the backlight and relays controller. The internal PC has 4 serial comm. ports, of which
COM4 is used to communicate with the backlight controller (see above scheme). In situations
where an external PC is used, ILStranslator needs to know to which comm. port.
Note that only the Comm port can be changed. The other communication parameters are fixed.