CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 45)

Chapter 4 Data Interfaces
RS-449/422 Model 422
45
The SD, RD, ST, RT and TT pins carry the primary data and clock signals (conforming to the RS-
449 and RS-422 standards). In addition, an extra clock signal input (conforming to RS-422) is
provided to make the 2240/-422 combination more "DTE-like" in tail circuit applications at the
clock source end. The remainder of the pins are either ground references or control signals.
Send Data (SD) and Receive Data (RD) are the data input and output signals for the modem,
respectively.
Send Timing (ST) is the modem’s transmit clock reference output that is used for the internal and
slave clock modes. Receive Timing (RT) is the clock signal for the receive data unless the 2240’s
Table 4-3. RS-449 Pinouts
Pin
Number
A/B
RS-449 PIN
Name
(abbrev)
(full name) Direction
1 SHLD shield -
4/22 SD send data to modem
5/23 ST send timing from modem
6/24 RD receive data from modem
7/25 RS request to send to modem
8/26 RT receive timing from modem
9/27 CS clear to send from modem
10 LL local loopback to modem
11/29 DM data mode from modem
12/30 TR terminal ready to modem
13/31 RR receiver ready from modem
14 RL remote loopback to modem
15 IC incoming call from modem
17/35 TT terminal timing to modem
18 TM test mode from modem
19 SG signal ground -
20 RC receive common - (tied to SG)
33 SQ signal quality from modem
34 NS new signal to modem
37 SC send common to modem
2/36* N/A extra clock for
receive data to modem
* The extra clock is an enhancement added to -422 interfaces. Any -
422 interface card outfitted with this capability can be identified via
the lack of the W16/W15 BAL_CTRL jumper. The W16/W15 jumper
was never described in the manual, so do not try to find a reference
to it in the manual.