Specifications

Reference Guide
2-9
Applications Data Modules and Applications
should occur when the HSU port and the attached device are connected over a long cable. The
Data Polarity may be inverted to ensure the density for Nx64 Kbps data circuits supporting
HDLC-based protocols that are connected to non-B8ZS T1 facilities.
The “Clear To Send” control lead may always be set to high, low or local mode. In local mode,
the CTS signal reflects the state of the Request To Send (RTS) signal that is received from the
attached DTE device. In that mode, the delay between RTS and CTS is software set-able, with
options of 0, 30, 60 or 100 milliseconds. Additionally, if the HSU port is programmed to
operate at Nx56 Kbps, then RTS will be transmitted end-to-end and presented as RLSD at the
far end of the circuit.
Software-initiated diagnostics support include the setting of local loop backs towards either
the network or the attached DTE equipment. Additionally, a remote loop back function allows
the HSU card to generate three DDS-compatible latching loop back codes for the far-end
OCU, CSU and DSU equipment. Similarly, the HSU data port may be programmed to detect
and respond to both latching and non-latching DDS-format OCU, CSU and DSU loop back
codes initiated from the remote end of the circuit. A time-out option authorizes the HSU port
to automatically release the loop back after ten minutes. This feature applies to an HSU port
that is running at 56 Kbps or for super-rate circuits if the loop back code is transmitted in the
first super-rate’s DSO. The card can also generate and recognize two industry standard
in-band loop-up and loop-down codes that act on the entire super-rate circuit. Those are the
ITU (CCITT) V.54 code and the ANSI Fractional T1 code.
Additionally, the integral Bit Error Rate Tester (BERT) can be used to generate test patterns
and route those towards the WAN facility. These test patterns can then be used to verify
synchronization and measure circuit quality. For further information regarding Performance
Monitoring and Diagnostic Capabilities, see Chapter 8, System Testing and Diagnostics.
Applications
There are several business applications the integrated access system equipped with an HSU
card supports.
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LAN to LAN
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LAN to WAN to LAN
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Work Station to Computer
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Computer to Computer
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Compressed Video
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CAD/CAM
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Call Center