Cooper Menvier 100, Руководство по установке, Страница: 13 / 38

Menvier40/100 Before You Begin
Page 9
(parallel) configuration at the control unit
connector.
Figure 11 Bus Wiring Configurations
For star configurations the cable length
from control unit to the most distant bus
device should be kept short, and should not
exceed 100m. There should be no more
than four arms in the star.
For a daisy chain configuration the total
cable length should not exceed 1,000m.
Bus Termination
The control unit bus uses the RS485
interface. Because of this the ends of the
line in some configurations may be
terminated to improve performance in
electrically noisy environments or where
there are long cable runs. The control unit.
expanders and keypads have a termination
link on their PCBs (see 3 in Fig 3 for the
control unit and 5 in Fig 8 for the keypad).
Fitting a jumper to the pins adds a
termination to the cable.
In a daisy chain configuration fit the
termination jumpers in the devices at each
end of the chain (see Fig 11 ).
In a star configuration:
If there are only two arms on the star
then this is the same as a daisy chain
configuration (see “Daisy Chain 1” in
Figure 11). If required fit the
termination jumper at the devices on
the end of each arm.
If there are more than two arms AND
two cables are long while the remaining
cables are short (less than 10m) then it
is possible to terminate at the two
devices on the ends of the long cables.
If there are more than two arms BUT
each cable is more than 10m then
DO
NOT fit the termination jumpers on any
of the devices.
Voltage Drop
In order for the system to work correctly,
the voltage at each device must NOT drop
below 10.5V even when running on the
standby battery. Cooper Security
recommend that the voltage at each device
should stay above 12V.
Standard 7/0.2 alarm cable has a
resistance of 8 Ohms per 100m per core.
The voltage drop is calculated using the
following formula: V Drop = Current drawn
x cable length x 0.08 x 2.
Table 1 shows the voltage drop against the
current drawn and cable length.
The shaded area shows where the voltage
drop would cause the bus voltage to fall
from 13.8V to below 12.0V when using a
single core.