Resolve address notation first
A manual may use a reference such as 40001 while a client expects a zero-based protocol address. Document the notation on both sides and test one known register. Do not apply an offset to the whole map until a known value confirms it. Use read functions during initial mapping.
Test values that reveal mistakes
Use a documented test condition that exposes sign and word order. A small positive integer can look correct under several wrong interpretations. Compare a negative value where supported, a non-integer engineering value and a counter transition. Capture raw bytes with the decoded result so the check can be repeated.
Keep scaling separate from transport
Record data type, register width, byte order, word order, scale and unit as separate fields. A pressure that is ten times too large may be a scale problem, not an endian problem. Validate at two or more points within the expected operating range and confirm the device behavior for invalid readings.
Save the acceptance evidence
For each critical tag, keep the device reference, raw response, expected result, observed result and test date. Confirm that timeout or exception responses produce a bad-quality state rather than a believable zero. Approve the map with the automation owner before any downstream report depends on it.
Put it into practice
Use the related tool to check your assumptions, then bring the results to your project discussion.