Ø
Problems in practical connection
In some circumstances user adopts a star
configuration in practical connection. The
termination resistors must be connected to the two
equipment 1# and 5# in picture 10-4.4. As the star
configuration is not in conformity with the
requirements of Rs485 standards, problems such as
signal reflections, lower anti-
interference performance arise when the cables are
long in the connection. The reliability of control
signals is decreased with the phenomena that the dome
does not respond to or just responds at intervals
to the controller, or does continuous operation
without stop.
Trouble
Possible cause
Solution
Dome can
do self-testing
but cannot
be controlled
The dome can
be controlled
but the operation
is not smooth
A Chage the address and baud rate of controller or dome
B Adjust the + and -connection of Rs485
C Make sure the connections are fully seated
D Change Rs485 Bus wires
、
、
；
、
；
、
A
Secure the connection
B
Replace Rs485 bus wires
C
Add termination resistors to the system
D
Install Rs485 distributor
、
；
、
、
、
Ø
Rs485Bus troubles shooting
Rs4 85Dis tribu tor
B-
1#
2#
3#
12 0
Ω
12 0
Ω
12 0
Ω
A+
Picture 10-4.5
1#
32#
15#
6 #
M ai n contr oller
Picture10-4.4
120
Ω
12 0
Ω
In such circumstances the Factory recommends
the usages of Rs485 distributor. The distributor can
change the star configuration connection to the mode
of connection stipulated in the Rs485 standards. The
new connection achieves reliable data transmission.
(Refer to picture 10-4.5)
A The address and baud rate setting of dome
are not in conformity with those of controller.
B The + and - connection of Rs485 Bus is incorrect
C bad connection
D there are circuit in the Rs485Bus
、
、
、
、
。
A the Rs485Bus is not in good contact with the connectors
B One wire of Rs485bus is broken
C The dome is very far from controller
D There are two many domes connected in the system
、
、
、
、
38
Appendix
