4-18
User Manual CM-CAN1
4 Setting the device parameters
4.6.2 Writing string
parameters
The master enters in data byte 2 the code for “Write string parameter”.
Data bytes 3-6 are of no significance in block 0. In the reply telegram from
the drive unit a status message is entered in block 0 in data byte 2. If the
status is 0, write access is permitted and the master begins transmitting
the first strings.
The master transmits 4 characters per data block. The last-but-one data
block must contain a 0 terminator. For the purposes of synchronization,
the drive unit sends each data block back to the master.
Explanatory note on checksum: Blocks 1 to n - 1 by logical XOR linking of
data bytes 3 - 6.
Telegram sequence
Action
Base
ID
Data byte 2
(selector)
Data bytes 3 - 6
For data format
see below
Data byte 7
(counter)
Master job 1101 SEL_String (8) xxxx 0
Drive unit reply 1321 Status (0) xxxx 0
If status = 0 and string longer than 3 characters, 2nd block follows
Master job 2 1101 SEL_String (8) 4 characters 1
Drive unit reply 1321 Status (0) 4 characters 1
Last but one block
Master job n-1
1101
SEL_String (8) 0-3 characters, 0
terminator
Number of blocks - 1
Drive unit reply
1321
Status (0) 0-3 characters, 0
terminator
Number of blocks - 1
Last block
Master job n 1101 LIST_End (16) 32-bit checksum Number of blocks
Drive unit reply 1321 Status (0) 32-bit checksum Number of blocks
Table 4.11 Telegram sequence, writing 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
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