Case · Transport · Legacy serial protocol

New controllers.
The airport's own language.

An international airport in Southeast Asia · baggage handling system. The flight signs at the sorting chutes got new c-power controllers. The airport system that drives them did not change.

Integration: Existing serial protocol
Controller: C-Power 10B · custom firmware
Link: LAN → serial gateway → RS-485
Display: 2 sides × 6 lines × 8 characters

The sign, running its rules

Replica · sample flight numbers

Green is an opened flight. Amber is not opened yet. When a line has more than one flight, the sign rotates them inside a 16-second cycle. Pick a line to see its timing.

Left · L

Right · R

Line L4 · flights on this line

Reduced motion · manual controls

Three flights: the first shows for 8 seconds, the second and third for 4 seconds each.

16-second cycle

XV 0772
8sXY 0904
4sXZ 2210
4s

Frame anatomy

What line L4 looks like on the wire

Each frame carries the sign address, colour and characters for one line. Pick a part to see what it does.

ADDRESS

Names the sign column the frame is for. Each controller reacts only to its own address, so signs can share one RS-485 bus.

How the job was done

The controller learned the old protocol, so nothing upstream had to.

01 · Challenge

The baggage system already sent flight data to the signs in its own serial format. The signs needed new LED controllers that would accept that data as it was.

02 · Constraints

Upstream software stays unchanged
Same serial gateways and RS-485 bus
Fixed layout: 6 lines × 8 characters per side
Colour carries meaning: green open, amber not opened
Rotation timing set by the operator's rules

03 · Approach

Custom firmware parses the legacy frames on the controller
Each column answers its own address, with a reply frame
A custom character file matches the sign's lettering
A config file fixes the screen size, so the sign starts in its layout
Bench-tested frame by frame over RS-485

04 · Result

The new controllers drop into the existing bus and show the same information the operators already rely on. The airport side kept its software, gateways and wiring.

Signal path

From the baggage system to the LEDs

04 · NEW · C-Power 10B

Listens on the bus, takes only frames with its own address, verifies the checksum, sends a reply frame and draws each character in its colour with the custom lettering.

Project specification

Controller: C-Power 10B
Firmware: Custom build with the site's serial protocol parser
Interface: RS-485, reached through LAN-to-serial gateways
Layout: Left and right sides, 6 lines × 8 characters each
Colours: Green (opened) · amber (not opened)
Lettering: Custom character file
Start-up: Screen size fixed by config file

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