Billboard Lighting and Status Control System
While at Sherwood Engineering, I did some design work on a billboard lighting control and status system.
The base system used an Intel 80286 processor mounted on a custom printed circuit card. Attached to the card was
a Mobidem modem that could send and receive data communications packets. Software for the system was written in
C language, and some assembly language as well. The system would control the turn on and turn off of the huge
(400W) billboard lamps in accordance with a programmed schedule. If a lamp went out, the base unit detected
the condition and transmitted a fault message so the billboard operator would be advised of the outage.
Here are some pictures of the base unit:
I wrote a little of the software for the base unit, and also designed a tester for it.
The tester software was written in Visual C++.
The base unit attached to several relay/sensor modules which were daisy-chained together.
These modules would actually turn on the billboard lights in response to commands from the base unit,
and would also detect when a light went out. Each module contained a MicroChip PIC processor containing
software written in assembly language. The module communicated with the base unit using a serial communications
protocol (a custom protocol with an RS-485 physical layer as I recall).