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7 • MODBUS PROTOCOL USE (SLOT 5 HOST COMMAND/RESPONSE)
In slot 5, 8 bytes are available in input and 8 bytes are available in output in order to encapsulate the modbus rtu
protocol in the process data.
These data contain:
Offset
0
Host Command byte 0-1
2
Host Command byte 2
3
Host Command byte 3
4
Host Command byte 4
5
Host Command byte 5
6
Host Command byte 6
7
Host Command byte 7
Offset
0
Host Response byte 0-1
2
Host Response byte 2
3
Host Response byte 3
4
Host Response byte 4
5
Host Response byte 5
6
Host Response byte 6
7
Host Response byte 7
Normally, in idle condition, the value of this word is the same as the RESPONSE TRIGGER WORD�
To enable the command, proceed in sequence:
1.
prepare the command in the fields from Host Command byte 2 to Host Command byte 7 according to need
2.
increase the value of the command trigger word
3.
wait for the value of the response trigger word to be the same as the command trigger word
When the command is complete or in idle condition, its value is the same as the command trigger word
Identifies the node number of the slave concerned
Supports commands 1, 2 (read bit); 3, 4 (read a word); 5 (write 1 bit); 6 (write a word)
80561A_MSW_GFW-Profinet_07-2018_EN
7�1� Request channel
SLOT 5 HOST COMMAND
Item Name
7�2� Response channel
HOST RESPONSE
Item Name
7�3� Command trigger word
7�4� Response trigger word
7�5� Command node address/response node address
7�6� Command Modbus Function Code
Meaning
Command Trigger word
Node address
Modbus Function Code
Data 1
Data 2
Data 3
Data 4
Meaning
Response Trigger word
Node address
Modbus Function Code
Data 1
Data 2
Data 3
Data 4
19
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