The four properties, as they appear in a Modbus network include two for the “byte-order” that devices use for sending or receiving 4-byte (32-bit) data values in Modbus messages. Separate settings are for float (floating-point) and long (integer).
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Float Byte Order
Choices reflect two alternate methods, where numerals 0, 1, 2, and 3 represent the least significant byte to most significant byte, as follows:
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Order3210— Most significant byte first, or “big-endian”, it is the default. -
Order1032— Bytes transmitted in a 1,0,3,2 order, or “little-endian”.
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Long Byte Order
Choices reflect two alternate methods, where numerals 0, 1, 2, and 3 represent the least significant byte to most significant byte, as follows:
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Order3210— Most significant byte first, or “big-endian”, it is the default. -
Order1032— Bytes transmitted in a 1,0,3,2 order, or “little-endian”.
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Float or long values received in incorrect byte order may appear abnormally big, or not at all.
The other two properties depend on the Modbus function codes supported by child devices, which (if available) provide alternative options in Modbus messaging for write actions:
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Use Preset Multiple Register
Function code 16 support (Preset Multiple Registers) is available in devices (true or false). The default is false, where function code “Preset Single Register” is used in place.
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Use Preset Multiple Coil
Function code 15 support (Preset Multiple Coils) is available in devices (true or false). The default is false, where function code “Preset Single Coil” is used in place.