Installing the KF3
Chapter 2
28
Cabling for the RS-232C connector of the KF3 will vary depending on
your application. The pinouts for this connector are given in Table 2.B.
Table 2.B
RS232C Connector Pinouts
Signal
Abbreviation
Direction
Pin No.
Meaning
Chassis Ground
-
-
1
The cable shield must be connected to chassis ground at one
end only.
Transmit Data
TXD
Output
2
RS232C serialized data output from the module.
Receive Data
RXD
Input
3
RS232C serialized data input to the module.
Request to Send
RTS
Output
4
A request from the module to the modem to prepare to
transmit. With fullduplex protocol, RTS is always asserted.
With halfduplex protocol, it is turned on when the module has
permission to transmit, otherwise it is off.
Clear to Send
CTS
Input
5
A signal from the modem to the module that indicates the
carrier is stable and the modem is ready to transmit. The
module will not transmit until CTS is on. If CTS is turned off
during transmission, the module will stop transmitting until
CTS is restored.
Data Set Ready
DSR
Input
6
A signal from the modem to the module that indicates the
phone is offhook. It is the modem's answer to DTR. The
module will not transmit or receive unless DSR is on. If
the modem does not control DSR properly, DSR must be
jumpered to a high signal at the module. (It can be jumpered
to DTR.)
Signal Ground
GND
-
7
Signal ground - a reference point for the data signals.
Data Carrier Detect
DCD
Input
8
A signal from the modem to the module to indicate that the
carrier from another modem is being sensed on the phone
line. It will not be asserted unless the phone is offhook.
Data will not be received by the KF3 unless DCD is on. With
fullduplex protocol, the module will not transmit unless DCD
is on. If the modem does not control DCD properly, DCD must
be jumpered to DTR at the module.
Data Terminal Ready
DTR
Output
20
A signal from the module to the modem to connect to the
phone line (i.e., pick up the phone"). The module will assert
DTR all the time except during the phone hangup sequence.
Modems built to North American standards will not respond
to DTR until the phone rings. The KF3 module will not work
correctly with modems which always pick up the phone upon
receiving DTR, whether the phone is ringing or not.
RS232C Cabling
Considerations
