User Manual

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Building Technologies M-bus System CE1P5361en
HVAC Products 5 Engineering 08.02.2007
5.5 RS-485 port
5.5.1 General
 The signal converter is connected to the OZW10 via the RS-485 port
 The M-bus protocol serves as the transmission protocol at the RS-485 port
 The only bus topology permitted is line topology
 The cable used is a twisted 2-core cable
5.5.2 Planning
 A maximum of 1 signal converter WZC-P250 or 1 signal converter WZC-P60 can
be connected to the OZW10. It is not recommended to connect WZC-P250 signal
converters in parallel as these produce an additional load on the M-bus
 The maximum cable length for all permitted rates of data transmission
(300…9,600 Baud) is 1000 m, based on a cable diameter of 0.8 mm. The maxi-
mum cable length is not restricted by the proposed protection circuit
5.5.3 Protection against transients
In principle, the regulations are the same as those for the M-bus. For details, refer to
section 5.4.3 “Protection against transients“.
5.5.4 Electrical installation
 When laying the RS-485 cable, the local regulations for electrical installations must
be complied with
 For important information about compliance with EMC directives, refer to Data
Sheet N2034