# Check Modbus byte order

READ-ONLY · YOUR APPROVAL · NOT FOR BIT ORDER

Determine byte order without another device read. Give the skill the raw words from one saved sample. It calculates the value for every supported byte and word order. You compare those values with what you know about the equipment.

## One sample, all supported orders

A 32-bit sample produces the ABCD, BADC, CDAB, and DCBA results. The evaluation does not send another Modbus request. A 64-bit sample produces every supported four-word order. Keep the device, register, time of the read, and raw words together.

## When to use it

Use this skill when raw words exist and the map does not define byte order. If no sample exists, use $capture-sample first.

## Workflow

1. Read the saved sample.
2. Calculate every supported order.
3. Confirm the value that matches the equipment.
4. Add the confirmed layout to the map.

Coil or packed-bit numbering is a $check-map hold. Resolve it through map review with an explicit bit-numbering rule. It is not an ABCD, BADC, CDAB, or DCBA question.

## Prompt

```text
Use $check-byte-order to calculate every supported byte and word order for these raw words. Show me each value. Do not choose an order until I confirm which value matches the equipment.
```

## Safety

No writes. No broadcasts. No discovery scans. No polls without a defined limit. Unknown values stay blank and appear in the review list.

Source: https://github.com/studioxvii/modbus-skills/blob/main/plugins/modbus-skills/skills/check-byte-order/SKILL.md