Why write the mapping down
A device reports raw numbers: a count from a CAN frame, millivolts from an analog input, a bit from a digital input. The platform shows a parameter with a name and a unit. Between the two sits a scaling that someone entered once, often from memory.
When a graph looks wrong a year later, a written mapping tells you whether the fault is in the vehicle, the device setting or the platform.
What each column means
Source tells you where the value comes from. Raw type and raw unit describe the number before scaling. Factor and offset turn it into a physical value. Physical unit and platform parameter say what the platform shows. The low and high alarm limits are the values at which you will set an alert, so they can be checked later.
Bytes and byte order
A signal that is two bytes long can be sent low byte first or high byte first. J1939 sends the low byte first. The Reference sheet has a small helper: type the two bytes in decimal, choose the order and it gives the raw value. Always confirm the order in the document for your vehicle.
Testing a row
Put a known raw value in the Test raw column, work out what the platform should show, then read what it does show and type it in. If the two agree within the tolerance the row passes. Test at least two values for a row with an offset, so you catch a wrong sign.
Limits of this sheet
It records a mapping and a test. It does not know your vehicle: every factor and offset is yours to enter and verify. It is not a certificate or an approval.