Browse Prior Art Database

Point-Of-Sale Terminals With Loop Trace Function

IP.com Disclosure Number: IPCOM000060812D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Orr, MA: AUTHOR [+2]

Abstract

This article describes a technique and apparatus whereby an ordinary point-of-sale terminal can be used as a test equipment terminal for observing data on the communications loop. The figure shows a communications network wherein a plurality of terminals are coupled to a store controller by the loop communications medium. A well-known SDLC (synchronous data link control) protocol is used to transmit messages between the terminal and the controller. All messages placed on the data loop by the controller or a terminal are preceded by an address. Under normal operating conditions each terminal on the loop is given a unique loop address or addresses. This address is used to identify messages from the terminal to the store controller, or vice versa.

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Point-Of-Sale Terminals With Loop Trace Function

This article describes a technique and apparatus whereby an ordinary point-of- sale terminal can be used as a test equipment terminal for observing data on the communications loop. The figure shows a communications network wherein a plurality of terminals are coupled to a store controller by the loop communications medium. A well-known SDLC (synchronous data link control) protocol is used to transmit messages between the terminal and the controller. All messages placed on the data loop by the controller or a terminal are preceded by an address. Under normal operating conditions each terminal on the loop is given a unique loop address or addresses. This address is used to identify messages from the terminal to the store controller, or vice versa. The loop communications adapter, not shown in the figure, is integral with the terminal. The adapter will receive only those messages carrying the address of a specific terminal. In order to use a terminal as test equipment, a loop communication trace facility function is placed inside each of the terminals. With this function, if messages need to be monitored on the loop in order to solve a communication problem, separate test equipment does not have to be brought in as it was in the prior art. By placing this trace facility function in the terminal two problems are solved: namely, test equipment does not have to be brought in from another location and the terminal or loop...