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Chapter 2
Installing the KF3
Modem Cabling
Considerations
2 12
The KF3 is connected to a modem via a direct 25-pin-to-25-pin cable,
which you must construct using Belden #8723 (or equivalent) cable.
Important: The length must not exceed 50 feet, and the cable shield must
be connected to chassis ground (using Pin 1) at the KF3 end only.
Figure 2.17
Connection between a KF3 and a Modem
KF3
1
TXD 2
RXD 3
RTS 4
CTS 5
DSR 6
GND 7
DCD 8
DTR 20
The KF3 can be connected to standard asynchronous dial-up modems.
Important: Some modems are designed to respond to the DTR signal by
answering the phone whether it is ringing or not. Since the KF3 asserts
DTR at all times except during the hang-up sequence, the phone would
always appear to be "busy." Do not use the KF3 with any type of modem
that answers the phone as soon as DTR is asserted.
The types of dial-up network modems that you can use are:
Manual: These are typically acoustically coupled modems. The
connection is established by human operators at both ends, who insert
the handsets into couplers to complete the connection.
DTE Controlled Answer: These unattended modems are directly
connected to the phone lines. The KF3 serves as the data terminal
equipment to control the modem via the DTR, DSR, and DCD signals.
The module incorporates timeouts and tests to properly operate these
types of modems.
Shield
Modem
2 RXD
3 TXD
4 RTS
5 CTS
6 DSR
7 GND
8 DCD
20 DTR
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