SST Automation GT200-PN-RS, User Manual

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Pin Function
1 TXD, RS-232 data sending, Connect RXD of user device
2 RXD, RS-232 data receiving, Connect TXD of user device
3 GND
2.3.3 Serial II-RS485
Pin Function
1 D+, RS485 Data Positive, connect Data Positive of user device
2 D-, RS485 Data Negative, connect Data Negative of user device
3 GND
2.3.4 Standard RS485 Characteristics
The basic characteristics of RS485 transmission technology:

Network topology: Linear bus, there are active bus terminal resistors at both sides.
 Transmission rate: 1200 bps~115.2Kbps.
 Media: Shielded twisted-pair cable and also can cancel the shielding, depending on environmental
conditions (EMC).

Site number: 32 stations per subsection (without repeater), and can increase up to 127 stations (with
repeater). When serial port 1 and serial port 2 simultaneously connect the slave equipment as the Modbus
master or User config, serial port 2 can configure up to 3 nodes. When configuring serial port 2 as the
Modbus master independently, it can configure up to 4 nodes.
 Plug connection: 5-pin pluggable terminal.
The main points on the installation of RS485 transmission equipment:
 All the equipment are connected with RS485 bus;

The farthest two end of the bus has a terminal resistor—120Ω 1/2W to ensure reliable operation of the
network.

Serial interface uses 5-pin pluggable open terminal and user can wire it according to the wiring instructions
D+
D-
GND