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5.6
Special Functions for Modbus RTU modules
I/O Modules R/W Error Control Entry
The I-7232D Manufacturer Specific Profile Area defines some special
functions for Modbus RTU modules. The object with index 0x2000 is the I/O
modules read/write error control entry. Each sub-index of this object is mapped
to the corresponding Modbus RTU module except sub-index 00.
For example, there are 4 Modbus RTU modules connected with the
I-7232D, and the module address for each Modbus RTU module is 1, 3, 4, and
5 respectively. Sub-index 1 is mapped to the Modbus RTU module with
address 1. Sub-index 2 is mapped to the Modbus RTU module with address 3
Sub-index 3 and sub-index 5 are mapped to the Modbus RTU module with
address 4 and 5 respectively, and so the sub-index 0 will be 4. This means that
there are 4 Modbus RTU modules connected with the I-7232D. If accessing
the I/O channels on the Modbus RTU modules fails, the value of the
corresponding sub-index will count times of the errors which occur according
to ether a read/write timeout or read/write failure. The counting range is from 0
to 65535, and the counting value may be returned to 0 after 65536. It can be
cleared to 0 via the SDO communication method.
I-7232D CANopen/Modbus RTU Gateway user manual (Version 1.02, December/24/2008) ------166