CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 42)

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Canoga Perkins
4.2 RS-423 / 232D Model 432
NOTE: The maximum data rate for this interface, 153.6 kbps, is
limited by the interface driver slew rate.
This interface is electrically compatible with EIA RS-423A. It will also operate with
RS-232D systems when adhering to the more limiting RS-232D specifications
(20 kbps and 2500 pF cable capacitance). EIA standard RS-423A does not
reference physical connector types or pinouts.
This interface uses the physical connector type and pinouts specified in RS-232D
(refer to Table 4-A). The RS-423/232D interface uses a 25-pin female D-type
connector for the physical connection.
The TD, RD, SCT, SCR and SCTE pins carry the primary clock and data signals.
The remaining pins are either ground references or control signals.
Transmit Data (TD) and Receive Data (RD) are the data input and output signals
for the modem. Serial Clock Transmit (SCT) is the modem’s transmit clock
output used for the Internal and Slave modes. Serial Clock Receive (SCR) is
always the clock signal for the Receive Data. Serial Clock Transmit External
(SCTE) is the clock signal input used in External Clock Mode.
None of the control leads interact with the data transmission. The control leads
are provided in order to comply with a variety of DTE interface requirements.
Most of the control leads are actually end-to-end signal channels which can be
used for any purpose as long as it conforms to the electrical interface standards of
RS-232D or RS-423A. One example of this would be asynchronous data trans-
mission at rates up to 19.2 kbps (30% jitter due to sampling at 64 kHz).
The RTS, CTS and DCD pins function together to provide the most common
handshake functions. An input to RTS (see description of RTS-Bias jumper) is
transmitted to the DCD output at the other end of the link (see description of DCD
jumper). CTS follows RTS locally but it is delayed by approximately 1 msec
when RTS turns ON (see description of CTS-Gate jumper).
There are four other end-to-end control lead pairs. They are listed below with the
input signal listed first:
STD to SRD SRTS to SDCD
DTR to RI DSRS to SCTS