18
Appendix
: The Cleaning of Clear Down Cover
To obtain constant clear videos, user should clean the down cover periodically.
z
Be cautious when cleaning. Hold the down cover ring only to avoid direct touch to the acrylic
down cover. The acid sweat mark of fingerprint will corrode the coating of down cover and
scratch on down cover will cause vague images.
z
Use soft dry cloth or the substitute to clean the inner and outer surfaces.
z
For hard contamination, use neutral detergent. Any cleanser for high grade furniture is
applicable.
Appendix
: RS485 Bus Basic Knowledge
1. Characteristics of RS485 Bus
As specified by RS485 standards, RS485 Bus is of half-duplexed data transmission cables
with characteristic impedance as 120 . The maximum load capacity is 32 unit loads
(including main controller and controlled equipment).
2. Transmission distances of RS485 Bus
When user selects the 0.56mm (24AWG) twisted pair wires as data transmission cable, the
maximum theoretical transmitting distances are as follows:
Baud Rate
Maximum Transmitting Distance
2400 Bps
1800m
4800 Bps
1200m
9600Bps
800m
If user selects thinner cables, or installs the dome in an environment with strong
electromagnetic interference, or connects lots of equipment to the RS485 Bus, the maximum
transmitting distance will be decreased. To increase the maximum transmitting distance, do
the contrary.
3. Connection and termination resistor
The RS485 standards require a daisy-chain connection between the equipment. There must
be termination resistors with 120 impedance at both ends of the connection (refer to Picture 40).
Please refer to Picture 41 for simple connection. “D” should not exceed 7m.
120
. . . . .
120
1#
2#
3#
4#
32#
Figure 37
A+
B-
D
120
A+
B-
. . . . .
. . . . .
120
M ain controller
1#
2#
3#
31#
Figure 38
The connection of 120
termination resistor: The termination resistor is ready on the
Protocol PCB. There are two kinds of connection. Refer to the Protocol PCB jumper setting
