Страница 1 мировой engineering стандарты общая спецификация

8.12.2.2 Request Message Data Parameter Definition. 
Table 133 contains the data parameter values
defined for this service.
Page 157
GM WORLDWIDE ENGINEERING STANDARDS
GMW3110
Table 133: Request Data Parameter Definition
Definition
dataFormatIdentifier
This data parameter is a one byte value with each nibble encoded separately. The high nibble specifies the
compressionMethod
, and the low nibble specifies the 
encryptingMethod
. The value “$00” specifies that
neither compressionMethod nor encryptingMethod is used. If no compression or encryption techniques are
used, the unCompressedMemorySize bytes are transmitted as part of the request but their values may be
ignored by the ECU.
UnCompressedMemorySize
This data parameter can vary from two to four bytes based on the needs of the ECU (e.g., length of modules to
be downloaded). The same number of bytes shall always be used for this parameter in all RequestDownload
service requests for a given ECU. A programming tool determines the number of bytes to transmit on the bus
based on data contained in the utility file (reference the programming chapter within this specification and also
the Interpreter Specification listed in the Normative References section of this specification for more details). If
compression or encryption techniques are used during programming, the data contained in the
unCompressedMemorySize parameter shall be used by the Node to compare against the uncompressed size
of the total data transferred with subsequent TransferData ($36) service requests. The total data transferred
can either be a large block of data that contains all software and calibration modules (single service $34
request), or a block of data that contains a single software or calibration module (multiple service $34 requests,
one for each module).