Kantronics KPC–3 Plus User Manual page 37

Make Your Serial Cable
This section is for those making your own cable instead of purchasing one.
We assume that if you are making your own cable you are familiar with the process and
just need to know: (1) what parts are needed, and (2) how the parts are connected.
Parts needed:
a male DSUB-25 connector, to connect to the KPC-3 Plus' (female) ―Computer‖
port,
either a female DSUB-9 or a female DSUB-25 connector, depending on the
connector on your computer's serial (COM) port, to connect to the computer's
(male) serial (COM) port,
an appropriate length of high quality shielded cable with 5 or more wires,
as shown below, if you are using a DSUB-9 connector, either 5 or 8 wires can
be connected and any other wires are unused,
as shown below, if you are using a DSUB-25 connector, either 5 or 9 wires
can be connected and any other wires are unused.
Note: You must terminate the shield on each end of the cable assembly properly. See
Note 2 in the Radio Frequency Interference Statement section.
Wiring instructions:
Some third-party software does not use hardware flow control and therefore does
not need the RTS and CTS wires shown below.
For details on preparing your cable wiring, use the chart below that is appropriate for
your configuration. In each case, there is a listing of which KPC-3 Plus (―Computer‖
port) pin needs to be connected to which pin on the computer's serial (COM) port. The
wiring depends upon whether your computer has a 25-pin connector or a 9-pin
connector, and on how many wires are in the cable (you only need 5 wires connected
for KPC-3 Plus operations, but you may connect more wires to use the cable for other
purposes). See page 209 for a diagram showing pin numbers on a DSUB-25 connector.
CASE 1-A: Wiring if computer has a 25-pin connector and the cable has 5 wires:
KPC-3 Plus
2 <——> 2 TXD
3 <——> 3 RXD
4 <——> 4 RTS
Computer
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