Specifications
1-2
PA-8T-V.35 Synchronous Serial Port Adapter Installation and Configuration
OL-3563-03
Chapter 1 Overview
Serial Interface Specifications
Figure 1-1 PA-8T-V.35 Port Adapter—Faceplate View
All PA-8T-V.35 serial interfaces support non return to zero (NRZ) and non return to zero inverted (NRZI)
format, and both 16-bit and 32-bit cyclic redundancy checks (CRCs). The default configuration is for
NRZ format and 16-bit CRC. You can change the default settings with software commands.
There is no default mode or clock rate set on the PA-8T-V.35 serial ports, although an internal clock
signal is present on all ports for data communications equipment (DCE) support. The internal clock
allows you to perform local loopback tests without having to terminate the port or connect a cable. To
use the port as a DCE interface, you must set the clock rate and connect a DCE compact serial cable. To
use the port as a DTE interface, you need only connect a data terminal equipment (DTE) compact serial
cable to the port. Because the serial adapter cables determine the mode and interface type, the
PA-8T-V.35 interface becomes a DTE when a DTE cable is connected to it.
If a DTE cable is connected to a port with a clock rate set, the DTE ignores the clock rate and uses the
external clock signal that is sent from the remote DCE. For a brief description of the clock rate
command, see the “Configuring Timing (Clock) Signals” section on page 5-10. For complete command
descriptions and instructions, refer to the publications listed in the “Related Documentation” section on
page viii.
Serial Interface Specifications
Serial signals can travel a limited distance at any given bit rate; generally, the slower the bit rate, the
greater the distance. All serial signals are subject to distance limits beyond which a signal degrades
significantly or is completely lost. Table 1-1 lists recommended transmission speeds and distances for
V.35 serial interfaces. The recommended maximum rate for V.35 is 2.048 Mbps.
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SERIAL-V.35
Table 1-1 Recommended Transmission Speed Versus Distance
V.35 Distances
Rate (bps) Feet Meters
2400 4,100 1,250
4800 2,050 625
9600 1,025 312
19200 513 156
38400 256 78
56000 102 31
2048000 25 8