Values are 10, 100, or 1,000 times too large or too small
Separate raw decoding, scaling, and unit conversion, and apply each once.
Trace the conversion
- Check the raw word(s), start address, type, and order first. Scaling the wrong raw number can accidentally produce a believable result.
- Find the map's factor and offset. For a linear definition, engineering value = decoded raw value × scale + offset. Raw 215 with scale 0.1 and offset 0 is 21.5.
- Check the specified unit. W and kW differ by 1,000; Wh and kWh also differ by 1,000. Power and energy are different quantities.
- Inspect the client driver's conversion and the displayed point's conversion. Remove an unintended second application of the same factor.
- Check for a separate scale/exponent register or an installation-specific ratio where the manufacturer requires one. Obtain its documented value rather than guessing.
SB1000's TCP → RTU forwarding does not apply its MQTT/BACnet library scaling to the external client's replies. Configure the external client using the field device's map.
Expected result
Raw data and the documented conversion explain the final value and unit exactly. Record each stage of that conversion if further help is needed.