User Manual

12
Siemens AG
A6V11185116_en_a
Building Technologies 2017-08-11
Third-party bus
(Modbus RTU or BACnet MS/TP)
A+, B-, REF (T5)
RS485 (EIA-485)
1 interface on terminal T5
Bus connection A+, B-, REF
Bus protocols Modbus RTU mode or BACnet MS/TP
Bus electronics
not galvanic isolated
Bus cable Shielded twisted pair (like AWG 24)
Bus polarization Switchable by software (680 Ω)
Baud rate 600, 1200, 2400, 4800, 9600, 19200, 38400
Bus termination None (require external termination, e.g. 150 W)*
*
It is essential to use a network termination on each end of the RS485 line, which
matches the cable impedance to prevent signal reflections and corrupting the data on
RS485 network.
Tools/HMI
Local service interface
(T-HI)
Cable connection RJ45 jack, 8 pins, length of cable <3 m
Local-HMI
RS-485 (EIA-485) not galvanic isolated
Bus polarization 680 Ω / 680 Ω
Bus termination 120 Ω / 1 nF
Supply voltage
DC 24 V, Max. 100 mA
(short circuit protected)
Tool
USB Use PC service cable POL0C2 for tools