User Manual
Modbus/BACnet IP Gateway
GT200-BM-2RS
WWW.SSTCOMM.COM
10
Pin
Function
1
B+, RS485
2
A-, RS485
3
GND
The RS-485 interface of GT200-BM-2RS is a standard one, and the RS-485 characteristics of the product are
shown as follows:
1. The basic characteristics of RS-485 transmission technology
①
Network topology: Linear bus, there are active bus terminal resistors at both sides.
②
Transmission rate: 1200 bps~115.2Kbps.
③
Media: Shielded twisted-pair cable and also can cancel the shielding, depending on environmental
conditions (EMC).
④
Site number: 32 stations per subsection (without repeater), and can increase up to 127 stations (with
repeater).
⑤
Plug connection: 3-pin pluggable terminal.
2. The main points on the installation of RS-485 transmission equipment
①
All the equipment are connected with RS-485 bus;
②
Each Subsection can be connected up to 32 sites;
③
The farthest two end of the bus has a terminal resistor - 120Ω 1/2W to ensure reliable operation of the
network.