General Specification Electrical Function gmw3110 General Motors Local Area Network Enhanced Diagnostic Test Mode Specification

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 21 of 336 
New Request 
Addressing Type 
Previous Request 
Addressing Type 
Handling in the Tester 
Functional with 
response 
Functional with 
response 
Wait until the completion of the previous functional 
request that requires a response (positive response, or 
negative response other than $78) before transmitting the 
next functional request that requires a response. 
Functional with 
response 
Functional without 
response 
Wait 30 ms after the transmission of the functional 
request that does not require a response before 
transmitting the functional request that requires a 
response. 
4.3.2 Node (ECU) Rules. 
1. The node shall be able to receive and process all tester requests which comply with the above rules. 
2. If a polling rate is used by an ECU to service CAN controller message object(s), then the polling rate for 
diagnostic message object(s) shall be < 30ms. 
Note:
The above rule provides the tester a fixed maximum wait time between requests to avoid overwriting 
diagnostic requests in the ECUs receive message object(s). This wait time does not apply to the case where a 
physical request is followed by a functional request that does not require a response (e.g., physical request 
followed by a functional TesterPresent) or the case where a functional request that does not require a 
response is followed by a physical request (e.g., functional TesterPresent followed by a physical request) 
– 
refer to paragraph 4.3.1. 
Note:
There is also a requirement for devices on the Low Speed GMLAN subnet to be able to transition into 
high speed operation during programming within 30 ms of receiving a request to do so. Therefore polling rates 
for these devices must already be less than 30 ms. Refer to the programming section of this specification and 
diagnostic services $A5 and $20 for additional information.