FieldReg – Modbus Decoder

The register decoder that lives in your pocket — and never phones home.

You're at a panel with a flow meter publishing FLOAT32 and a SCADA tag that reads garbage. FieldReg decodes 1, 2, or 4 Modbus registers into every interpretation simultaneously — signed and unsigned integers, FLOAT32/64 — in all four byte orders (ABCD, CDAB, BADC, DCBA), with a plausibility flag that points at the value that makes physical sense.

Decode — hex or decimal entry, smart paste, swap word order in one tap, automatic history.
Address — protocol address ↔ 1-based ↔ 40001 ↔ 400001, with read/write function codes per entity.
Scale — linear scaling, 4–20 mA loop calculator with NAMUR range flags, 0/25/50/75/100 % injection tables you can export as CSV straight into the loop-check record. Save instrument presets.
Bits & CRC — tappable 16-bit grid, hex/decimal/binary/octal live, CRC-16/MODBUS with the on-wire byte order spelled out.
Reference — eight offline field sheets: function codes, exception codes, RTU/TCP framing, RS-485 wiring, serial gotchas, data types, PLC addressing, 4–20 mA.

100 % offline. No account. No analytics. No tracking. Your register values never leave the device — the App Store privacy label reads "Data Not Collected" because nothing is.

Free forever: 16-bit decode, FLOAT32 in all four orders, and the address converter. One affordable one-time purchase unlocks the rest — no subscription.

Made by a controls engineer, for the people standing in front of the panel.

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