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

8.12.8 Tester Implications. 
This service should only be physically addressed (point to point). The number of 
bytes to use in the uncompressedMemorySize parameter is determined from data within the utility file. 
The device must be unlocked prior to requesting data downloads to the device. While this mode does not 
require TesterPresent messages, the following modes, which are required to be active prior to requesting 
mode $34, do: 

$27 (to keep the device unlocked if the download block is a secured memory area). 

$28 (to keep normal communications disabled). 

$A5 (to keep programming mode active). 
8.13 TransferData ($36) Service. 
This service is used to transfer and/or execute a block of data, usually for 
reprogramming purposes. 
8.13.1 Service Description. 
The TransferData service shall be used to download a block of data, download 
and execute a block of data, execute a resident routine, or execute a previously downloaded block of data. To 
execute a previously downloaded data block, use a download and execute transfer type (sub-parameter = $80) 
with zero data bytes being transferred. A node resident routine could be executed using the download and 
execute transfer type (sub-parameter = $80) and identifying the routine in the startingAddress parameter or by 
putting a routine number in the dataRecord field. 
This service is indirectly secured by the RequestDownload ($34) service. The RequestDownload ($34) service 
must be performed successfully prior to executing this service in order to prepare the targeted node to accept 
the TransferData message(s). Once service $34 has been performed successfully, it shall be possible to carry 
out one or more TransferData service requests. 
Note:
Successful completion of a RequestDownload ($34) request also requires that security must be 
unlocked (via SecurityAccess $27 service if applicable), that normal communications have been disabled (via 
DisableNormalCommunication $28 service) and that the ProgrammingMode ($A5) service has been activated. 
These services ($27, $28, and $A5) require the tester to send TesterPresent ($3E) requests at least once 
every P3
C
ms in order to keep them active. 
A single TransferData message is limited to a maximum of 4095 total data bytes (including the Service 
Identifier byte, sub-function $Level parameter, address bytes, and data bytes). An ECU with limited RAM 
resources may further restrict the maximum number of bytes transferred with a single request of this service. 
During SPS programming, the programming tool determines the maximum number of bytes to transfer from 
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