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Extended Diagnostic Feature Operation Disclosure Number: IPCOM000056201D
Original Publication Date: 1980-Nov-01
Included in the Prior Art Database: 2005-Feb-14

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Barlet, J Haas, L Hurel, D Smith, R Tyrrell, JM [+details]


In a data communication network comprising central station 1 and tributary stations 2, 3, modems MOD are used as interfaces between data terminal equipment DTE and the transmission channel. Test and alarm circuits TAC are associated with each modem. In a tributary station, circuit TAC detects a failure in the associated modem and sends an alarm tone on the transmission channel to the control station. In the control station, circuit TAC sends a tone on the transmission channel to the cards in the tributary stations to cause the associated modems to be switched to test mode.