Application of interfaces without data handling blocks Manual BG41/BG42/BG43
4-84 Rev. 99/49
4.2 Application of interfaces without data handling blocks
4.2.1 Address allocation
The building blocks occupy four (BG41) or eight (BG42, BG43) successive addresses in the PLC’s
address area. The setting of the base address, under which the building block should respond, is
described in chapter 5.1.
Each of the building block’s channels occupies 2 addresses, the data and the status register, whereby
channel 0 as the parameter channel is of particular significance.
Commands are transferred through channel 0, which modify the building block’s internal
parameters, e.g.:
•= Set clock,
•= Select procedure
•= Select baud rate
•= Set data format
Fig. 4-13: Data and status register of the BG41/2/3
Data/Status register
Each register has a register, through which data is exchanged bidirectionally between the PLC and
the building block, and a register, which communicates the status of the channel to the PLC. This
status register can only be read by the PLC.
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