FieldReg – Modbus Decoder

Decode PLC registers offline

Only for iPhone

Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.

iPhone

Every interpretation of a Modbus register at once — integers, FLOAT32/64, all four byte orders, with a plausibility flag that spots the right one. 100% offline. 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. — Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://aphelionengineering.com.au/fieldreg/privacy/

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The developer, Aphelion Engineering Pty Ltd, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

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    Accessibility

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    Information

    Seller
    • Aphelion Engineering Pty Ltd
    Size
    • 1.3 MB
    Category
    • Utilities
    Compatibility
    Requires iOS 26.0 or later.
    • iPhone
      Requires iOS 26.0 or later.
    • Mac
      Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 26.0 or later.
    Languages
    • English
    Age Rating
    4+
    In-App Purchases
    Yes
    Copyright
    • © 2026 Aphelion Engineering
  • Privacy Policy

    • More by Aphelion Engineering Pty Ltd

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