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3.3.4 I/O scanning to "Drive Profile Lexium"
I/O scanning is used for cyclic interchange of data between master
and slave.
I/O scanning must be configured on the master. The master can use 2
different approaches for of I/O scanning:
•
"Function Code" 23 (17
h
), Read-Write Mulitple Registers
•
"Function Code" 3 (03
h
), Read Multiple Registers and "Function
Code" 16 (10
h
), Write Multiple Registers
NOTE: The read value is 0 until the first write command is execu-
ted.
Settings The following setting must be made on the master before you can use
I/O scanning:
•
The "Unit Identifier" is 255.
•
The Modbus parameter address is 0.
•
The data length is 13.
In addition, you can use up to 3 mappable parameters. If these
parameters are used, the data length changes to 15, 17 or 19.
The Modbus addresses for I/O scanning do not differ from the
addresses for normal Modbus access.
Output - Input Output and input refer to the direction of data transmission from the
perspective of the master.
•
Output: Commands from the master to the slave
•
Input: Status messages from the slave to the master
3 Basics
LXM32M
22 Modbus-TCP module
0198441113843, V1.01, 01.2012