Xeo4 RILHEVA II, User Manual

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Protocol datatypes
LABEL TYPE ACCESS USE CASES
DISCRETES INPUT 1-bit READ ONLY Digital inputs
COILS 1-bit READ & WRITE Digital outputs
INPUT REGISTERS 16-bit READ ONLY Measures
HOLDING REGISTERS 16-bit READ & WRITE Working parameters, set-points
NB: the same data can be accessed by different access type
Data addressing
All the datatypes addressed by Modbus protocol (registers and coils) are zero based. The first register of
any kind has address 0.
Every datatype can sometime be specified with a starting prefix:
LABEL PREFIX
COILS 1xxxx
DISCRETES INPUT 2xxxx
INPUT REGISTERS 3xxxx
HOLDING REGISTERS 4xxxx
In this case, the address that must be used at Modbus protocol level is obtained by trimming the prefix and
substracting one.