CANOGA PERKINS 2240 Fiber Optic Modem User Manual
Page 48
2240 Fiber Optic Modem User Manual
Chapter 4 Data Interfaces
RS-530 Interface Model 430
48
which use RS-423 (unbalanced bipolar) electrical signals. Jumper options are detailed in the
following sections. The DB-25 pin assignments and signals supported are detailed in Table 4-4.
The interface connector is a female DB-25 with a separate 3.5 mm stereo phone jack that can be
used as an alarm contact input.
The TD, RD, SCT, SCR and SCTE pins carry the primary data and clock signals (conforming to
the RS-449 and RS-422 standards). In addition, the SCT leads can be reversed via a switch to
provide an extra clock signal input (conforming to RS-422) to make the 2240/-430 combination
more DTE-like in tail circuit applications at the clock source. The remainder of the pins are either
ground references or control signals. Transmit Data (TD) and Receive Data (RD) are the data
input and output signals to the modem, respectively.
Serial Clock Transmit (SCT) is the modem’s transmit clock reference output that is used for the
internal and slave clock modes. Serial Clock Receive (SCR) is the clock signal for the receive
data unless the 2240's main PCBA W26 (XTCLK) jumper is ON, in which case the Extra Clock
input signal is used to shift receive data out from the 2240. Serial Clock Transmit External
(SCTE) is the transmit clock signal used in either of the External Clock modes or when the main
board internal CLK/EXT switch is set to EXT (refer to section 3.7).
Two end-to-end control leads are provided as part of this interface. An input to RTS (Request To
Send) is transmitted to the DCD (Data Carrier Detect) output at the other end of the link (refer to
section 4.4.1 and section 4.4.2). The factory setting (refer to section 4.4.7) configures CTS as a
Table 4-4. RS-530 Signals and Pin Assignments
Pin
# A/B
Signal Name
Direction
FG
01
Frame Ground
-
TD
02/14
Transmit Data
to modem
RD
03/16
Receive Data
from modem
RTS
04/19
Request to Send
to modem
CTS
05/13
Clear to Send
from modem
DSR
06/22
Data Set Ready
from modem
SG
07
Signal Ground -
DCD
08/10
Data Carrier Detect
from modem
SCR
17/09
Receive Clock
from modem
SCT
15/12 *
Transmit Clock to/
from modem
SCTE
24/11
External Tx Clock
to modem
DTR
20/23
Data Terminal Ready
to modem
LL
18 **
Local Loopback
to modem
RL
21 **
Remote Loopback
to modem
TM
25
Test Mode
from modem
* Becomes extra clock input if SCT switch is set to IN position.
** These signals are single ended and activate a modem’s
system test. All other signals are balanced.