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3.4 SERIAL
This router also equipped with two serial ports which are RS232/422/485 ports that able to connect to local serial
devices. And these serial ports support TCP Server, TCP Client, and UDP Listening. From the web management
interface, it has two configuration pages for Serial 1 and Serial 2.
Below is the pin definition
Pin
RS232
RS485-4w/422
RS485-2w
1
DCD
TX-
Data-
2
TXD
RX+
-
3
RXD
TX+
Data+
4
DSR
-
-
5
GND
GND
-
6
DTR
RX-
-
7
CTS
-
-
8
RTS
-
-
9
RI
-
-
RS-232 is the most common serial interface and used to ship as a standard component on most Windows-compatible
desktop computers. Now it is more common to use RS-232 over USB using a converter. RS-232 only allows for one
transmitter and one receiver on each line. RS-232 also uses a Full-Duplex transmission method.
RS422 is an improved version of RS232, it uses twisted pair cable to reduce the noise, and it uses signaling balancing
to transmit data, so what is signal balanced – It uses a voltage-difference between the two lines as an indication of
the signal value, with this method the data is able to transmit for longer distance with faster data rates, with RS422
the data can transmit up to 10 Mbps at 50 feet or 100 Kbps at 4000 feet. RS422 is capable of multi-drop capability, it
limits up to 10 slaves in the data line.
RS-485 is a superset of RS-422 and expands on the capabilities. RS-485 was made to address the multi-drop limitation
of RS-422, allowing up to 32 devices to communicate through the same data line. Both RS-485 and RS-422 have
multi-drop capability, but RS-485 allows up to 32 devices and RS-422 has a limit of 10.
