Hardware manual PCD7.LRxx-PG5 room controller │ Document 27-653; version ENG07 │ 2019-03-21
Saia-Burgess Controls AG
Communication
5
5-16
Modbus on PCD7.LRxx-P5 RS-485 interfaces
E.g. the Modbus PCD FBox for a 32 bits signed integer must read on even ad-
dresses (with any length value):
1. Address 0, length 1 will copy R0 in Rbase
2. Address 2, length 1 will copy R1 in Rbase
3. Address 4, length 1 will copy R2 in Rbase
If only 16-bit accesses are supported (Modbus standard), you must read/write 2
consecutive holding registers starting at an even address, with an even length.
E.g. with the Modbus PCD FBox for a 16 bits signed integer:
1. Address 0, length 4 will copy
HR0 in Rbase,
HR1 in Rbase+1,
HR2 in Rbase+2,
HR3 in Rbase+3
2. Address 2, length 2 will copy
HR2 in Rbase,
HR3 in Rbase+1
