Port 502
In live entertainment systems, port 502 is used by Modbus TCP.
tcp/502
Modbus TCP — MODBUS/TCP application data units
The Modbus application protocol wrapped in a seven byte MBAP header and sent over TCP port 502, a plain register read and write protocol with no session and no security. In entertainment it is how show control talks to stage machinery PLCs, hoists, HVAC, house lights and building systems.
Check it from the command line
npx showstack port 502
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