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 15 of 336 
variables and flags used in the Node Interface Data Dictionary section of each diagnostic service. The 
common/global variables will be included in the data dictionary of each diagnostic service but reference this 
section of the document for further details. See Table 5. 
Table 5: Common/Global Pseudo Code Data Dictionary Global Variables 
Variable/Meaning
Power 
Up - S/W 
Reset 
Initial 
Value 
Values 
message_data_length 
This variable represents the length of the message received as 
determined by the network/transport layer PCI.DL_High nibble and 
PCI.DL_Low byte (if the message is more than one frame). This 
correlates to the Service Data Unit (SDU)  embedded in the 
N_USData.Ind service primitive as defined in ISO 15765-2 and 
OSEK/COM.
 
N/A 
1 to 4095 
message_address_type 
This variable represents the type of addressing used in the request 
message as determined by the network layer.
 
N/A 
FUNCTIONAL/PHYSICAL 
Dev_Cntrl_Active 
This flag used to indicate whether or not device control is currently 
active.
 
NO 
YES/NO 
request_DeviceControl_exit 
This flag is used in the DeviceControl logic to cancel active device 
control functions if a TesterPresent ($3E) timeout occurs or if a 
ReturnToNormalMode ($20) request is received.
 
NO 
YES/NO 
Diag_Services_Disable_DTCs 
This flag is used by the device to determine if any diagnostic service 
has been enabled which requires that Diagnostic Trouble Codes 
(DTC) be inhibited.