Modbus 32-bit float converter
Modbus devices commonly pack a measured value into two consecutive 16-bit registers as a single IEEE 754 32-bit float. Enter the eight hex digits read from the device and pick a byte order — big-endian or little-endian — to decode the number. Use it to sanity-check readings from PLCs, energy meters, flow computers and DAQ modules.
Modbus 32-bit float parser
Bytes as parsed: 66 246 0 0. Bytes are parsed most-significant first, matching a device configured for big-endian register output.
Parsed with DataView.getFloat32 — big-endian reads 42 F6 00 00 as 123.0; little-endian reads the same bytes as 00 00 F6 42. Spaces, dashes or colons between bytes are ignored.
Modbus registers below 40001 usually carry 16-bit words — a 32-bit float like the one above spans two consecutive registers. To read, scale or log such values you need gear that handles raw Modbus frames, such as industrial PCs, serial device servers and data acquisition modules. Browse them in the AO Ctrl catalog:
More calculator tools
Frequently asked questions
How do I decode a 32-bit float from two Modbus registers?
Enter the eight hex digits read from the device and pick a byte order. The calculator parses them as a single IEEE 754 32-bit float with DataView.getFloat32 — big-endian reads 42 F6 00 00 as 123.0, while little-endian reads the same bytes as 00 00 F6 42.
What is the difference between big-endian and little-endian float order?
Big-endian parses the bytes most-significant first, matching a device configured for big-endian register output. Little-endian is the byte-reversed reading — enter 00 00 F6 42 to get the same 123.0. The wrong order decodes a wildly different, usually tiny or enormous, number.
Why does my Modbus float read incorrectly with the wrong byte order?
Modbus packs a 32-bit float across two consecutive 16-bit registers, and devices differ in how they order those words and bytes. If the value looks like nonsense, toggle the byte order — the calculator also accepts spaces, dashes or colons between bytes in the input.