i-on1000EX
Before You Begin
Page 11
For a daisy-chain configuration, the total cable
length should not exceed 1,000m.
Note that if there are only two arms in a star
configuration, this is equivalent to a daisy-chain
configuration.
Bus Termination
The i-on1000EX 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
has a termination link for each bus (see Figure 3).
Expanders and keypads have a termination link
on their PCBs (see Figures 7, 11 and 13 for the
keypads). 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 Figure 17).
In a star configuration, terminate at the two
devices on the ends of the longest cables (see
Figure 17).
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.
Eaton’s Security Business 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.
Figure 17 Bus Termination