Auto-Diag-15: Read Scaling Data by Identifier — All Auto Tech

READ SCALING DATA BY IDENTIFIER

This service is used when the client wants to read any scaling data present in the ECU/server.

What is scaling data? What does it mean? It means a set of values that can be attributed in a formula can be read by the client. E.g. a signal value, such as analog input and output signals, and digital signals, any internal data, or any system-specific information.

The service ID is 0x24

The service is easily understood when explained with an example. So, let’s dive in.

Message Flow examples

We might have to see a couple of message flows to understand the service.

Request message

Positive response message

The response message would be to let the client know that the VIN is a 17 bit ASCII value and looks like

Decoding the response, we can see the scaling bytes are 0x6F and 0x62. What do they mean?

0x6F ->

• Higher nibble — 6 represents that the value is an ASCII value
• Lower nibble — F represents the total number of bytes, in this case, 15 bytes of VIN

0x62 ->

• Higher nibble — 6 represent an ASCII value
• Lower nibble — 2 represents the 2 leftover bytes of the VIN