Browse Prior Art Database

High Speed SDLC Passive Trace Machine

IP.com Disclosure Number: IPCOM000043356D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Williams, DD: AUTHOR

Abstract

The high speed Synchronous Data Link Control (SDLC) passive trace machine is a unique high speed device which can effectively be used in the debug and testing of a high speed SDLC communications protocol. An SDLC trace machine must be a passive machine. The trace must be performed totally transparent to the machines being traced. Also, it must have the capability of running continuously without intervention but must also be capable of "freezing" link activity on operator command. It must clearly separate different frames so that command and response sequences can be identified. Finally, if a frame is detected which would normally be ignored because of a transmission error, that frame should be separately identified and the reason for the reject condition also displayed.

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High Speed SDLC Passive Trace Machine

The high speed Synchronous Data Link Control (SDLC) passive trace machine is a unique high speed device which can effectively be used in the debug and testing of a high speed SDLC communications protocol. An SDLC trace machine must be a passive machine. The trace must be performed totally transparent to the machines being traced. Also, it must have the capability of running continuously without intervention but must also be capable of "freezing" link activity on operator command. It must clearly separate different frames so that command and response sequences can be identified. Finally, if a frame is detected which would normally be ignored because of a transmission error, that frame should be separately identified and the reason for the reject condition also displayed. Referring to the figure, the SDLC secondary is a smart terminal with an attachment feature that is used to interface the secondary to the SDLC link. The attachment feature is used as a receive-only device; that is, it only monitors link activity and never transmits on that link. The monitored SDLC activity is displayed via the terminal display. The display has an extensive display mode capability: normal, highlighted, reverse display, blinking and underscore. These display attributes are used to identify the different trace elements being displayed. The first byte displayed in the error frame is the status code and describes the reason the frame is invalid.

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