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DN1237-0003 © 1997-2000 Kantech Systems Inc.
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Combus Specifications
The Combus provides 500mA at 12 volt (13.85VDC). The recom-
mended cable is 22 AWG (Kantech part number: CBL-ZN). Each
loop (module to KT-300) cannot exceed 300 m (1000') and the total
maximum cable length of all connected loops cannot exceed 1200
m (4000').
For example:
•
Only four wireruns at 1000' from the KT-300
•
Only eight wireruns at 500' from the KT-300
•
Only ten (10) wireruns at 400' from the KT-300
Shielded wire should only be used in areas that present excessive
RF noise or electromagnetic interference. Modules can be straight
run, connected in a daisy chain or T-tapped anywhere on the
Combus.
During installation of the modules, it is necessary to inform the
system that new modules have been installed on the Combus. To
assign the modules to your system (software), see “assigning
modules” in the controller definition menu for detailed informa-
tion.
Combus Repower (if required)
Depending on how many modules are connected to the Combus
and how far they are from the KT-300 controller, you may need
to “repower” the controller’s Combus. The Combus needs to be
“repowered” if the voltage between the black and red wires of the
last module of each loop drops below 12.5 volt (the modules will
still operate but there will be no communication between the
modules and the controller and an event “Combus module defect”
will be generated from the controller). This voltage drops if
modules are drawing too much current (500mA maximum for the
Combus of each KT-300).
With a multimeter, you should verify this voltage and determine
if you need to install a KT-PC4204 in “repower” mode. Using this
configuration, you will be provided with an additional 1 amp of
current on the controller’s Combus. The KT-PC4204 is generally
installed at the beginning of the loop.
When using the KT-PC4204 in “repower” mode, the first relay of
the module will be reserved for the “repower function”. You will
have to assign an “all valid” schedule to the first relay so it is
“permanently activated” (see your software reference manual in
the “controller definition” menu under “assign modules” for the
exact procedure). If you are using a KT-PC4204 in “repower” mode
and other KT-PC4204 modules that are assigned as relays 1-4 or
KT-PC4216 modules that are assigned as relays 1-16 are also
connected to the same loop, do not use relay 1 of those modules
or relay 1 of the KT-300 door controller. Please also note that all
KT-PC4204 modules that are used for Combus repower should be
assigned as relays 1-4. The jumper 1 “J1” on the KT-PC4204 must
be moved to the Combus relay position.
Note: Do not use any power supply other than the KT-PC4204 to
repower the Combus. In the event of a power surge or transient,
a module may lock up and cease to communicate with the control-
ler. If the KT-300 loses communication with the module, it will
initiate a module reset and will power down the Combus for five
seconds in an attempt to reset the problem module. After five
seconds, the controller will reapply power to the Combus and the
problem module should begin to operate as intended.
