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Pelco Manual C539M-A (12/01) 25
Most of the time, connection cables are supplied with the device. As long as the supplied
cable is appropriate, no problem arises. If the cable length needed is greater than that sup-
plied, a problem arises for the installer/specifier as to the type of cable to use. One of the
most common hookup extensions is the remote hookup of a 9760 keyboard. The following
highlights the issues involved and ends with some recommendations.
For remote installation of a keyboard, the user must supply a cable of appropriate length
that supports the TIA/EIA-422-B (RS-422) communication standard. The example in
Figure 21 shows a keyboard placed 2,000 feet (610 m) from the CC1 via the user-supplied
cable. Junction boxes (phone boxes) are used to facilitate the RJ-45-to-cable connection
points at either end of the run. Note that only signal wires and ground are run through the
cable itself (five of the six available wires are used in the example). The transformer serves
to pass on the data signal and to supply power to the keyboard at the keyboard end.
Figure 21. Remote Wiring a CM9760-KBD
NOTE:
For short distances
that exceed the cable length
supplied, you might consider
the use of CAT 5 cable (for
distances up to 300 feet).
This cable is RS-422 compli-
ant (up to the length men-
tioned) and is used primarily
for Ethernet connections
within networks. Moreover,
it is readily available (be-
cause of demand) and cost is
reasonable (because it is less
difficult to manufacture).