Chapter 5 Communication
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Chapter 5 Communication
5.1 Communication connection
The RS485 communication interface of this controller has the characteristics of
isolation protection. It can be connected by ordinary twisted pairs (twisted
shielded wires).The wiring diagram is shown in Figure 2:
Figure 2 RS485 Communication wiring diagram
Notes
1.
A 120Ω terminating resistance R
T
can be connected in parallel at both ends
of the transmission lines A + and B- of the terminal equipment to effectively
reduce or eliminate signal transmission.
2.
Without repeaters, the maximum number of devices. The maximum
transmission distance is 1200m. For long-distance transmission, it is
recommended to use a cable designed for RS485 transmission.
3.
During communication, the baud rate, parity bit and stop bit of all devices on
the bus should be consistent, and the device addresses must not be the
same, so as to avoid communication abnormality caused by bus conflicts.
4.
The duration time for the host computer to wait for a response from the slave
computer generally needs to be greater than 0.5 seconds.
R
pull-high
R
T
R
pull-low
V
BUS
other
Modbus
d
evice
controller
ID:02
ID:01
A+
B-
C
ontroller
controller
