Automotive Diagnostics — Read Data By Identifier

The following services are categorized under the Data Transmission functional unit

READ DATA BY IDENTIFIER

The client will be able to read stored values in the server linked to some of the identifiers in the server. The data identifiers list should be present with the client to read the data, else, there would be a negative response sent by the server/ECU.

The service ID is 0x22

Important points about the Read Data by Identifier

• On receiving the request, the server/ECU accesses the data elements specified in the records and transmits the values in one single positive response to the client
• The client can request more than one identifier at the same time. The ECU would combine the data for all the identifiers in one single positive response to the client
• Some identifiers may require the security access granted to read the data from the identifier to keep the data share secure to known clients only

Message flow examples

Let’s look at an example where the client is trying to read two identifiers.

Assumption –

1. First Data Identifier (DID) client to read from ECU is 0x010A and second DID is 0x110