user manual

11
11.2.1.4 Data Integrity
As in all good protocols, there must exist a level of data integrity
checking to verify, with some degree of assurance, the quality of
the transmitted data. The Modbus protocol supports two types of
error checking:
• RTU Mode: 16 bit cyclic redundancy check (CRC-16)
• One bit parity check
CRC-16: When the master generates a message, a 16 bit CRC
value is added to the end of the transmitted packet. The CRC
value is generated using a series of the bit shifts and manipulations.
The receiving station executes the same calculation of the data
and verifies the transmitted CRC. Any discrepancy will cause the
message to be disregarded.
Parity: Parity checking can be added as an additional level of data security.
If parity checking is selected, even or odd parity can be implemented.
11.2.2 Modbus Register Map
A predefined register map has been provided for the T-3 unit. This
map is detailed in Appendix A.