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User Manual CM-CAN1
4-17
4 Setting the device parameters
DE
EN
1
2
3
4
5
6
7
A
Telegram sequence
Plausibility checks:
After the first block the existence and access rights of the parameter are
checked. If the drive unit inserts an error in the status of the reply
telegram of block 1, communication for the parameter in question is
terminated.
The last telegram contains the checksum of the overall string. If it is
wrong, or if the counter is incorrect, the transmitted string is not valid.
The telegram sequence within the drive unit is run according to a state
machine. This state machine is automatically reset if the master transmits
a telegram with an incorrect value for the block counter.
Action
Base
ID
Data byte 2
(selector)
Data bytes 3 - 6
(see below)
Data byte 7
(counter)
Master enquiry 1101 ENQ_String (11) xxxx 0
Drive unit reply
1321
Status (0) 4 characters for
status = 0 0
If status = 0 and string longer than 3 characters, 2nd block follows
Master enquiry 2 1101 ENQ_String (11) xxxx 1
Drive unit reply 1321 Status (0) 4 characters 1
Last but one block
Master enquiry 1101 ENQ_String (11) xxxx Number of blocks - 1
Drive unit reply
1321
Status (0) 0-3 characters,
0 terminator Number of blocks - 1
Last block
Master enquiry n 1101 ENQ_String (11) xxxx Number of blocks
Drive unit reply 1321 LIST_End (16) 32-bit checksum Number of blocks
Table 4.10 Telegram sequence, reading a string
Data bytes 3 - 6 are transmitted in Intel format:
Byte 3 = Low Word Low Byte
Byte 4 = Low Word High Byte
Byte 5 = High Word Low Byte
Byte 6 = High Word High Byte