CSE-H55N User
’
s Manual Ver. 1.2
- 59 -
http://www.ezTCP.com
9
RS485/RS422 Interface
9.1
About RS485/RS422 Network
The RS485 and the RS422 are the standards which communicate by differential voltage.
These transmission distances are much longer comparing to the RS232. The RS485 is multi-
driver/multi-receiver system but the RS422 is a single-driver/multi-receiver system.
9.2
Configuring an RS485 Network
The following is a general RS485 diagram.
TRX+
TRX-
GND
RX+
RX-
GND
CSE-H55N
TRX+
TRX-
GND
USER DEVICE
TRX+
TRX-
GND
USER DEVICE
TRX+
TRX-
GND
USER DEVICE
TR1
BR2
BR1
TR2
5V
Figure 9-1 General RS485 Network
9.2.1 Signal Ground
Even though the RS485 is known as a “two-wire” configuration, an additional ground
connection should be implemented.
If a signal ground is not used, there might be potential differences between nodes. And
it could be electrical noise or damages the transceivers.
9.2.2 Biasing Resistors
Two biasing resistors (a pull-up resistor and a pull-down resistor) should be in the RS485
Summary of Contents for CSE-H55N
Page 66: ......
