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9. IO Scanning service
9.1. Presentation
The IO Scanning service is used to exchange I/O data between: A controller or PLC (IO Scanner).
Devices (IO Scanning servers).
This exchange is usually performed by implicit services, thus avoiding the need to program the controller (PLC).
The IO Scanner periodically generates the Read/Write Multiple Registers (23 = 0x17) request.
The IO Scanning service operates if it has been enabled in the PLC and the drive.
The drive parameters assigned to IO Scanning have been selected by default. This assignment can be modified by configuration.
The drive IO Scanning service can also be configured by the option Modbus server.
When the IO Scanning service has been enabled in the
The parameters assigned in the periodic variables are exchanged cyclically between the option and the drive.
The parameters assigned in the periodic output variables are reserved for IO Scanning. They cannot be written by another Modbus service, even if the IO Scanner is not sending its periodic output variables.
9.2. Periodic variables
Word No. | Output variables (written by IO Scanner) | Input variables (read by IO Scanner) |
0 | Reserved | Reserved |
1 | Scanner write word 1 – configurable (c001) | Scanner read word 1 – configurable (c021) |
2 | Scanner write word 2 – configurable (c002) | Scanner read word 2 – configurable (c022) |
3 | Scanner write word 3 – configurable (c003) | Scanner read word 3 – configurable (c023) |
4 | Scanner write word 4 – configurable (c004) | Scanner read word 4 – configurable (c024) |
5 | Scanner write word 5 – configurable (c005) | Scanner read word 5 – configurable (c025) |
6 | Scanner write word 6 – configurable (c006) | Scanner read word 6 – configurable (c026) |
Reserved | Reserved |
It is possible to configure the assignment of periodic variables 1 to 6.
Please refer to "parameter" about configurable.
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