
Transmitting parameter data
Telegram structure
8
Networking via system bus (CAN)
8.4
8.4.1
L
8.4−2
EDSPM−TXXX−9.0−11/2009
Identifier
Instruction
code
Index
Subindex Data 1 Data 2 Data 3 Data 4
LOW byte HIGH byte
The instruction code contains the command to be executed and information about
the parameter data length. It is structured as follows:
bits 7
(MSB)
bits 6 bits 5 bits 4 bits 3 bits 2 bit 1 bit 0
Command Command Specifier (cs) Length E s
Write Request 0 0 1 0
00 = 4 bytes
01 = 3 bytes
10 = 2 bytes
11 = 1 byte
1 1
Write Response 0 1 1 0 0 0
Read Request 0 1 0 0 0 0
Read Response 0 1 0 0 1 1
Error Response 1 0 0 0 0 0 0 0
Instruction code for parameters with 4 bytes of data length:
4 bytes of data
(32 bits)
Command hex dec Information
Write Request 23 35 Transmitting parameters to a node
Write Response 60 96 Node response to the Write Request (acknowledgement)
Read Request 40 64 Request to read a parameter from a node
Read Response 43 67 Response to the read request with the actual value
Error Response 80 128 Node reports a communication error
If an error occurs, the addressed node generates an Error Response".
In Data 4, this telegram always contains the value 6", in Data 3 it contains an error
code:
Command code Error Response Data 3 Data 4 Error message
80
h
3
6
Access denied
5 Wrong subindex
6 Wrong index
Instruction code
Instruction Error Response"
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