HD-SDI High Speed Dome Camera
26
Please refer to below picture
for simple connection. Distance “D” should not exceed 7 meters.
(Picture 1)
(
Picture 2
)
3-2 The connection of 120 Ohm termination resistor:
The termination resistor is ready on the Protocol PCB. There are two kinds of connection. Please refer to the Protocol PCB
jumper setting form (refer to following pictures).
1) In the Picture it is the factory default connection. The jumper is seated on Pin2&Pin3 and the termination resistor is not connected.
2) when connecting the 120 Ohm termination resistor, user should pull out the protocol PCB and plug the jumper on Pin1&Pin2. Install
the PCB back and the termination resistor is connected. (
Appendix 9
:
5
、
RS-485 terminal resistor connection and operation )
4. 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 that are farthest away from each other, such as equipment 1# and 15# in the Picture as below. 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. ( refer to the following picture).
(
Picture 3
)
In such circumstances the factory recommends the usage 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 following picture).