ABB PSTX soft starter (built-in Modbus RTU)

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire; word order and scaling are only confirmed at the hardware-verified rung.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale
fbt_return_value	512	U16	1
programmable_analog_input_1	513	U16	1
programmable_analog_input_2	514	U16	1
programmable_analog_input_3	515	U16	1
programmable_analog_input_4	516	U16	1
programmable_analog_input_5	517	U16	1
programmable_analog_input_6	518	U16	1
programmable_analog_input_7	519	U16	1
programmable_analog_input_8	520	U16	1
programmable_analog_input_9	521	U16	1
programmable_analog_input_10	522	U16	1
fbt_control_word	768	U16	1
fbt_argument_2	769	U16	1
fbt_argument_3	770	U16	1

link settings as documented (unverified): RTU; FC 01,04,15,16; Requires setting parameters: FB interface connector to Modbus RTU, Fieldbus control to On, Com3 function to Modbus RTU slave.

⚠ The motor may start unexpectedly if there is a start signal present when doing any of the actions listed below: Switching from one type of control to another (fieldbus control/hardwire control), Reset all Settings — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	Com3
connector	FB interface connector
wiring notes	Uses RS485 / Modbus RTU
doc revision	1SFC132089M0201 July 2014

generated by gemini:gemini-3.5-flash · harvested from https://files.valinonline.com/userfiles/ct/documents/abb-drives/abb-pstx-modbus-rtu-guide.pdf (ABB); manual-faithful — the document's claims, panel risk: LOW — panel concurs, no field disagreements; proved interop-verified on 2026-06-11 · recorded 2026-06-11

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

Have a device that isn't here? Upload its register map — generation is free, and the connector earns its rung by being proven, not claimed.

Need it proven on your own device? Hardware verification — if it doesn't verify, you don't pay.

Building a platform? License the verified library — machine-readable maps, firmware matrix, API access.