The folder described behaviour and listed points, but nothing showed the
shape of the program. ARCHITECTURE.md covers what a reader needs before
opening any ST file:
- counts up front: 4 function blocks, 3 programs, 1 task, 69 located
variables, 65 process globals, 69 Modbus points, 1 comms interface
- the one architectural rule - only 10_globals.st and 50_prog_io_mux.st
may touch located variables, enforced by build.py - and why it is what
lets identical control logic run against a simulation or a real plant
- a layer diagram: Modbus slave / IO_MUX / CONTROL + its four FBs /
SIMULATION, with the direction of every flow
- what each of the 10 source files owns, with line counts
- execution order per build, and why SIMULATION runs first
- the 100 ms task interval is not independently adjustable: four POUs
integrate against a hardcoded SCAN_S := 0.1
- one comms interface, which is a runtime plugin rather than program
code - the reason 502 can be published and still refuse connections
- the 69 points by function code, with the %MW HR1024 warning
