In this case, it is recommended that a RS485 distributor being added. This product can change star connection
into a connection that accord with RS485 Industry Standard effectively, consequently, solve the problems, lift
communication liability, shown in figure five.
Figure 5
5. Common Malfunction and Solution of RS485 Bus
Fault
Phenomenon Probable
Cause
Solutions
1. The address or Baud Rate is not matched
between Host and the Speed Dome
1. Adjust the address or Baud Rate of Host or Speed
Dome to make a match.
2. RS485+,- are connected incorrectly
2.Change the RS485+ and RS485- wires
3. Wiring drops
3.fastening the wire
The speed
dome do the
self-check but
can not be
controlled.
4. RS485 wire broke
4. Change RS485 wire
1. loose contact of RS485
1. fastening RS485 wire
2. one RS485 wire broke
2. Change RS485 wire
3. Host and speed dome are too far away
3. Add terminal matched resistance
The speed
dome can be
controlled but
not smoothly
4. Too many speed domes are connected
4. Add RS485 distributor
20
