Browse Prior Art Database

Diagnostic Testing of CCITT V.35 and X.21 Interfaces

IP.com Disclosure Number: IPCOM000061254D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 67K

Publishing Venue

IBM

Related People

Alpers, TJ: AUTHOR [+3]

Abstract

This invention was developed to provide a diagnostic test for interfaces. These tests are used by the customer to prove that the system is fault-free when a possible phone company problem or modem problem exist. As a result, the system service cost is reduced. This invention eliminates the need for the system to be attached to a modem with diagnostic capability in order to verify that the system hardware and cables are operating correctly. In previous implementations, the modem was needed to provide a diagnostic clock. A diagnostic clock is multiplexed with an existing driver circuit (in diagnostic mode only). In one embodiment, additional electronics are added to a V.35 interface and a wrap connector is provided for the modem end of the cable. The chart below shows the signal names that are defined.

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Diagnostic Testing of CCITT V.35 and X.21 Interfaces

This invention was developed to provide a diagnostic test for interfaces. These tests are used by the customer to prove that the system is fault-free when a possible phone company problem or modem problem exist. As a result, the system service cost is reduced. This invention eliminates the need for the system to be attached to a modem with diagnostic capability in order to verify that the system hardware and cables are operating correctly. In previous implementations, the modem was needed to provide a diagnostic clock. A diagnostic clock is multiplexed with an existing driver circuit (in diagnostic mode only). In one embodiment, additional electronics are added to a V.35 interface and a wrap connector is provided for the modem end of the cable. The chart below shows the signal names that are defined. To provide the required differential diagnostic clock, the transmit data signal is used because it is the only differential system driver defined by recommendation V.35. To completely test the V.35 interface, the cable wrap test is done in two phases. Phase I uses transmit data as a diagnostic clock, and the wrap connector feeds it back as transmitter and receiver signal element timing. All other signals are wrapped by the added electronics at the system V.35 interface. Phase II uses the V.35 interface logic to provide transmitter and receiver signal element timing, and the wrap connector wraps the remaining control and data signals. In Fig. 1 during the phase I wrap, the SEL CLOCK lead is set to allow normal clocking to be received from an external source. The SEL WRAP lead is set so that the data and control signals will be wrapped at the interface logic and that external signals inputs will be ignored. The SEL WRAP will also cause the DIAG CLOCK signal to be gated onto XMIT DATA. The wrap connector then feeds this back to RSET and TSET; therefore, phase I verifies the operation of TSET and RSET. In Fig. 2 during phase II wrap, the SEL CLOCK lead is set to gate the diagnostic clock to both TSET and RSET with external inputs being ignored. The SEL WRAP lead is set so that the data and control signals are gated onto the cable. The wrap connector returns these signals as shown in Fig. 2. Phase II verifies the operation of XM...