Specify byte and word ordering before interpreting a wider Modbus value stored across multiple registers.
Preserve the wider-value representation
Schneider Electric documents selectable byte/word combinations for 32-bit values on a particular Modbus server. The wider-value contract must match both ends. Primary reference: 32-bit byte and word ordering.
This is evidence that a vendor-defined multi-register representation matters, not a universal default for all Modbus devices. Keep the actual application type and order together; interpreting four bytes as an integer and as a floating-point value is another distinct choice.
A hypothetical two-word example
Imagine the received words are hexadecimal 1122 and 3344. Combining them high-word first produces the integer pattern 11223344; reversing the word order produces 33441122. Both are mathematically possible combinations of the same two words. The device map must identify which pattern carries the intended value.
A byte swap within each word would introduce additional patterns. Do not diagnose a process jump from a decoded display before reconciling these representation choices. Record raw words, claimed type, expected ordering and a representative known-value assessment on the worksheet.
Review the complete decoding contract
Ask the supplier whether integer and floating-point fields use the same wider-word convention on the selected product. Preserve any configurable setting or firmware applicability in the interface record. Keep scale and engineering unit interpretations separate from the raw-pattern transformation.
This guide supplies no write instruction or conversion setting for an installed device. It assigns no Modbus implementation to HM equipment. Its practical result is a reproducible explanation of how the received register sequence becomes one documented wider application value.
Customer Questions
Does word order define signedness?
Type interpretation is separate.
Is the cited product’s default universal?
Use the selected device map.
Why retain raw register words?
They preserve the evidence before decoding.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
Discuss Your Machine Requirement
Share your product, container, required output and the evidence needed for your technical review.
Request a Technical Review