Long Distance Combus Extensions
The length of Combus from a PC4204CX Combus Regenerator can
be extended beyond 1000ft (305m), providing the following
conditions are met:
• Combus must be regenerated and repowered at both ends of
the wire run using the PC4204CX.
• No other modules are to be connected along the long distance
wire run.
• A maximum distance of 4000ft (1220m) can be achieved between
two PC4204CX devices. To extend further, additional PC4204CX
devices should be used.
NOTE: The wiring used to connect this equipment must be insulated with
PVC, TFE, PTFE, FEP, neoprene or polymide.
When extending Combus long distances, use the following chart to
determine what gauge of wire is necessary:
Maximum Length
AWG
2000ft (600m)
22
3000ft (900m)
21
4000ft (1200m)
20
Line Loss
When current is drawn through a piece of wire, voltage will be lost
due to the wire’s resistance. This voltage loss must be considered
for all installations.
To ensure proper operation, at least 12.5V
DC
must be applied to all
modules on the system (when AC is applied and the battery is fully
charged). If less than 12.5V
DC
is applied, system operation will be
adversely affected.
To correct the problem, try any or all of the following:
1. Connect another PC4204CX power supply near the module to
provide power to the Combus.
2. Reduce the length of the Combus run to the module.
3. Increase the gauge of wire.
Capacitance Limits
An increase in capacitance on the Combus will affect data
transmission and will cause the system to slow down. Capacitance
will increase for every foot of wire added to the Combus. The
capacitance rating of the wire used will determine the maximum
length of the Combus, between two PC4204CX Combus Repower/
Regenerator modules.
For example, 22-gauge, non-shielded, 4-conductor wire has a typical
capacitance rating of 20 picofarads per foot (which is 20nF/1000’).
For every 1000' of wire added – regardless of where it is run – the
capacitance of the Combus will increase by 20nF.
The following chart indicates the total Combus wire allowed
depending on the capacitance rating of the wire used:
Wire Capacitance per
1000’(300m)
TOTAL Combus Wire
Length
15nF
5300’/1616m
20nF
4000’/1220m
25nF
3200’/976m
30nF
2666’/810m
35nF
2280’/693m
40nF
2000’/608m
Wires run in parallel also increase Combus capacitance. For example,
when using 20nF wire, the following would be some of the
combinations allowed:
• Four wire runs at 1000'/305m each
• Six wire runs at 666'/203m each
• Eight wire runs at 500'/152m each
• 10 wire runs at 400'/122m each etc…
Contact the wire manufacturer for the capacitance ratings of the
wire being used.
3.4 Regenerating Combus
This module will regenerate the Combus signal as it passes from
one side to the other. The LEDs on the module will illuminate
whenever there is activity on either side of the input or output of
the module.
LED 1
LED 1
LED 1
LED 1
LED 1 illuminates when the module transmits data on ‘Combus In’
LED 2
LED 2
LED 2
LED 2
LED 2 illuminates when the module transmits data on ‘Combus Out’
The PC4204CX module will isolate ‘Combus In’ from any short
circuit problems on ‘Combus Out’. In the event of a problem, the
PC4204CX module will generate a module fault along with the
modules on the disabled Combus. This information can be used
to determine which section of Combus is disabled on the system.
When connecting the PC4204CX to the Combus, care must be taken
to ensure that the ‘Combus In’ terminals are connected to the
wires originating from the control panel (or a module that may be
situated between the PC4204CX and the control panel).
3.5 Applying Power
NOTE: Do not connect power until all wiring is complete.
After all wiring is completed, apply power to the control panel.
Connect the battery leads to the battery, then connect the AC
transformer. Then, connect power to the PC4204CX: first connect
the battery leads, then the AC transformer.
For more information on control panel power specifications, see
the control panel
Installation Manual
.
NOTE: It is the installer’s responsibility to provide adequate protection
for the transformer used in the primary and secondary circuit according
to the rated current of the transformer. The transformer used must be Class2,
Fail Safe as defined within EN61558-1 and must meet the applicable
requirements of the EN60950 Standard. A readily accessible disconnect
device must be incorporated into the fixed wiring and must disconnect
both poles simultaneously. The wiring connected to the PC4204CX must
be mechanically protected, routed, supported, clamped or secured in a
manner that prevents excessive strain on wire and terminal connections,
loosening of terminal connections and conducter insulation damage.
NOTE: Do not connect fully discharged (less than 10V) or damaged
batteries to the PC4204CX.
4. Enrolling the Module
Once connected, the module must be enrolled on the system. To
enroll the module, perform the following:
1. Enter installer’s programming by pressing [*] [8] [Installer’s Code].
2. Scroll to “Module Hardware” and press the [*] key.
3. Scroll to “Enroll Module” and press the [*] key.
4. Scroll through the different modules until “PC4204” is displayed.
Press the [*] key.
5. The message “Create Tamper on Desired Unit” will be displayed.
To create the required tamper, secure the tamper zone on the
module and then open it. The transition from secure to violated
enrolls the module. After this is done, the keypad will display
the module number and will confirm enrollment (e.g., “PC4204
Mod 01 Enrolled”).
For more information regarding module enrollment, see the control
panel
Installation Manual
.
