Modbus 40001

Modbus 40001 is a Modbus/TCP master for testing and commissioning industrial equipment — PLCs, drives, meters, and controllers — from an iPhone or iPad. Enter a device's IP address and port, choose a function code, and continuously poll a block of coils or registers of any size. Values update live, changed cells flash as they move, and holding registers and coils can be written back with a tap. FEATURES • Function codes 01–04 — Coil Status, Input Status, Holding Register, Input Register • Any block size — set the start address and length, checked against the protocol limits for each function • Poll rates from 100 ms to 5 seconds • Value notations — unsigned and signed decimal, hex, binary, 32-bit long, Float32 and 64-bit double in both word orders • Character notations — ASCII in either byte order, plus a low-byte form, with a joined readout so device names and serial numbers read as text • Writes — tap a cell to send Preset Single Register (06) or Force Single Coil (05) • Multiple scan documents — save several register blocks per device and switch between them • Addressing toggle — 1-based (PLC style) or 0-based (raw protocol), so off-by-one confusion is a single tap away from being resolved • Traffic view — every frame in and out as bracketed hex, with capture and clear • Status strip — polls, valid responses, errors, success rate, latency, and last update time • Built-in demo device — try every screen without hardware on the bench • Designed for both orientations — iPad keeps a two-column layout, iPhone scrolls the whole page No accounts, no analytics, no advertising. Device addresses and scan settings are stored only on your device. Intended for general testing of the Modbus/TCP protocol. Not certified for safety-critical use.