View source for Roadmaster LED Signboard

The NODE has a Roadmaster RRDS100H LED Signboard.  This page details what we know about it.

Programming occurs over IR, and it looks like the device reports out what it's displaying
on a single LED on the back as well.  The small board with the IR demodulator and red (IR?)
LED on it is labeled "3-750 B.pcb".  The 4-wire connector to it breaks out: two pins
(1 [square pad] and 3) go to the IR demodulator, pin 2 goes to the LED, and pin 4 seems to
be ground.