HF2221 Serial Server Device User Manual
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2.2. RS232 Interface
Device serial port is male(needle), RS232 voltage level(can connect to PC directly), Pin Order is
cosistent with PC COM port. Use cross Cable connected with PC(2-3 cross, 7-8 cross, 5-5 direct, 7-8
no connection), see the following table for pin defination.
Figure 4. RS232 Pin Defination(Male/Needle Type)
Table 3. RS232 Interface
Pin Number
Name
Description
2
RXD
Receive Data
3
TXD
Send Data
5
GND
GND
7
RTS
Request to Send
8
CTS
Clear to Send
2.3. RS485 Interface
RS485 use two wire links, A(DATA+), B(DATA-). Connect A(+) to A(+), B(-) to B(-) for communication.
The RS485 interface support maximum 32 485 device, special hardware version can support max 255
device. The cable maximum length is 1200 meters. Need to add 120Ohm terminal resistor for over
300 meters.
2.4. RS422 Interface
RS422 interface use T+/T-/R+/R-, cross connect to device as the following picture.
Name
Description
TX+
Transfer Data+
TX-
Transfer Data-
RX+
Receive Data+
RX-
Receive Data-
