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PA-4T Synchronous Serial Port Adapter Installation and Configuration
OL-3560-02
Chapter 1 Overview
Synchronous Serial Specifications
Synchronous Serial Specifications
The PA-4T provides up to four synchronous serial interfaces. Each interface allows a maximum
bandwidth of 2.048 Mbps; the speed depends on the type of electrical interface used. Use EIA/TIA-232
for speeds of 64 kilobits per second (kbps) and below, and use X.21, EIA/TIA-449, V.35, or EIA-530 for
higher speeds.
Serial signals can travel a limited distance at any given bit rate; generally, the slower the baud 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 the recommended (standard) maximum speeds and distances for each PA-4T serial
interface type. The recommended maximum rate for V.35 is 2,048 Mbps.
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232. The
recommended distance limits for EIA/TIA-449 shown in Table 1-1 are also valid for V.35, X.21, and
EIA-530. EIA/TIA-449 and EIA-530 support 2.048-Mbps rates, and V.35 supports 2.048-Mbps rates
without any problems; we do not recommend exceeding published specifications for transmission speed
versus distance. Do so at your own risk.
LEDs
The PA-4T contains the enabled LED, standard on all port adapters, and a one status LED for each port.
After system initialization, the enabled LED goes on to indicate that the PA-4T has been enabled for
operation. The LEDs are shown in Figure 1-2.
Figure 1-2 LEDs on the PA-4T—Horizontal Orientation Shown
Table 1-1 Standards for Transmission Speed Versus Distance
EIA/TIA-232
Distances
EIA/TIA-449, X.21, V.35, EIA-530
Distances
Rate (bps) Feet Meters Feet Meters
2400 200 60 4,100 1,250
4800 100 30 2,050 625
9600 50 15 1,025 312
19200 25 7.6 513 156
38400 12 3.7 256 78
56000 8.6 2.6 102 31
1544000 (T1) – – 50 15
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