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memorySize
The parameter memorySize is used to select the number of consecutive memory addresses (in ascending
order) to be read starting at memoryAddress (memorySize includes the starting location). The contents of the
range of addresses defined by memoryAddress and memorySize are provided in the positive response
message. memorySize shall have a value between 1 and 4092 bytes if a 2-byte memoryAddress parameter is
used (4091 if 3-byte addressing is used and 4090 if 4-byte addressing is used). The maximum value comes

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25.06.2020
WORLDWIDE ENGINEERING STANDARDS General Motors Local Area Network Enhanced Diagnostic Test Mode Specification
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from the maximum number of bytes allowed by the USDT protocol, less the bytes for the response service
Identifier and the address information from the request message which is included in the response. An ECU
may choose to limit the maximum value of memorySize based on ECU resources (e.g., the size of the Network
Layer Buffer). If an ECU limits the maximum value of the memorySize parameter, then the maximum allowed
value shall be documented in the appropriate CTS or SSTS.
8.7.3 Positive Response Message Definition (Table 93).
Table 93: ReadMemoryByAddress Positive Response Message
Data Byte
Parameter Name
Cvt Hex Value Mnemonic
#1
ReadMemoryByAddress Positive Response Service Id
M
63
SIDPR
#2
#3
#4
#5
memoryAddress = [
memoryAddress (Byte1 - MSB),
memoryAddress (Byte2),
memoryAddress (Byte3)
memoryAddress (Byte4)] 
Note 1
M
M
C3
C4
xx
MA_
#4/5/6
#5/6/7
:
#n
memoryDataRecord = [
memoryData #1,
memoryData #2,
:
memoryData #m]
M
xx
MDREC
C3: Byte 3 is present when the memoryAddress parameter contains 3 or 4 bytes.
C4: Byte 4 is present when the memoryAddress parameter contains 4 bytes.
Note 1: 
Byte1 in the memoryAddress parameter is always the most significant byte of the address and the last byte of the memoryAddress
parameter (Byte2 for 2-byte addressing, Byte3 for 3-byte addressing, or Byte4 for 4-byte addressing) is always the least significant byte of
the memoryAddress parameter.
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