How exactly are you wiring the RS-232? From what I can find, the sign has a 6-pin RJ-11 (telephone) connector, with pin 6 being ground, pin 3 RS-232 TXD, pin 4 RS-232 RXD. (pins numbered from left to right, connector tab on top).
How exactly are you wiring the RS-232? From what I can find, the sign has a 6-pin RJ-11 (telephone) connector, with pin 6 being ground, pin 3 RS-232 TXD, pin 4 RS-232 RXD. (pins numbered from left to right, connector tab on top).