18
Figure 7-2
7.4
RS485 Bus FAQ
Phenomenon
Possible Reasons
Solution
Speed dome
can run self-
diagnosis but I
can not control
it.
z
Host address(baud rate) and
speed dome address(baud rate)
are not match;
z
Positive and negative end of
RS485 Bus are misconnected;
z
Connection cable is loose
；
z
RS485 Bus connection are cut
off;
z
Modify host or speed dome setup
；
z
Switch RS485 positive end and
negative end
；
z
Fix connection cable firmly
；
z
Replace RS485 Bus.
I can control
the speed
dome but is not
smooth
z
RS485 Bus connection are not
good
；
z
One RS485 bus is off
；
z
The distance between host and
speed dome is too far
；
z
Parallel connected too much
speed domes.
z
Connect RS 485 Bus again
；
z
Replace RS485 Bus
；
z
Add terminal matching resistance
；
z
Add
RS485
distributor.
