Page
Chapter: 1
Section:
5
CONFIGURATION
1.2.1.2 CONNECTOR X2.
It is a SUB-D type 9-pin female connector for the RS-422 serial port connection.
The cable shield must be connected to pin 1 of the connector at both ends of the cable.
CONSIDERATIONS FOR THE RS-422 INTERFACE
It uses two separate cables for each signal. This presents the following advantages:
- It increases noise immunity.
- It allows data transmission over greater distance for the same baudrate.
- It reduces problems due to different ground potentials and interference between
signals.
The RS422 standard does not define the communications protocol to be used. It can be
used together with the RS499 standard.
A line terminating resistor must be installed between pins 3 and 8 (transmit data) as well
as between pins 4 and 5 (receive data). These resistors must be placed at both connectors
and its value must match the characteristic impedance of the cable.
Typical value : 120 Ohms 1/4W.
Atention:
Do not manipulate the connectors with the unit connected to main AC
power
Before manipulating these connectors (inputs/outputs, feedbach, etc)
make sure that the unit is not connected to main AC power
PIN
SIGNAL
FUNCTION
1
FG
Shield
2
----
No connected
3
/TxD
Transmit data
4
/RXD
Receive data
5
RXD
Receive data
6
----
No connected
7
GND
Ground signal
8
TxD
Transmit data
9
----
No connected
REAR PANEL
