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

Table 220 and Table 221
for the detailed definition of the 
HFI. 
M 
--``,,``````,``,,``,,,`,`,`,,-`-`,,`,,`,`,,`---
CameraLoops.com

---

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 263 of 336 
Offset 
Number 
of Bytes 
Name 
Description 
Cvt 
$05 
4 to 16 
SWMI 
This is a variable-length field that contains the 
SWMI
(refer to 
DID $C1 thru $CA definitions in Appendix C) data reported 
via the $1A service. The Header Format Identifier field 
contains length information for this field of the header.
M 
End of 
SWMI 
+ 1 
2 to 3 
DLS 
This is a variable length field that contains the modules 
D
esign 
L
evel 
S
uffix (
DLS
) or Alpha Code (ASCII)
M 
End of 
previous 
field 
+ 1 
2 
DCID_ 
This optional field is present if the H_N
Size
bit of the HFI is 1, 
and the DCID bit in the HFI field is also a 1. This field is two 
bytes in length and contains a Data Compatibility identifier 
value. For an operational software module header this value 
is compared against a constant in the bootloader to ensure 
that the software being downloaded is compatible with the 
boot software in the ECU. For a calibration file header this 
value is compare by the programming executive against a 
corresponding value in the operational software header to 
ensure that there is no mismatch between the calibration file 
and the operational software. 
U 
End of 
previous 
field 
+ 1 
1 to 2 
NOAR 
This optional field is present if the