Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Remote Modem Control

IP.com Disclosure Number: IPCOM000042567D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Choquet, M: AUTHOR [+3]

Abstract

A modem is, by definition, transparent to data. This means that the terminal cannot communicate with it using the data leads unless the modem has been told by another means that the message sent by the terminal must be interpreted. This problem has occured at the implementation of remote modem test applications. One solution may be provided by using the test control (TC) lead. This solution has a serious limitation. The modem must be physically directly connected to the terminal through the EIA interface. In order to solve this problem, it has been proposed to replace the physical TC lead by logic information.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 90% of the total text.

Page 1 of 1

Remote Modem Control

A modem is, by definition, transparent to data. This means that the terminal cannot communicate with it using the data leads unless the modem has been told by another means that the message sent by the terminal must be interpreted. This problem has occured at the implementation of remote modem test applications. One solution may be provided by using the test control (TC) lead. This solution has a serious limitation. The modem must be physically directly connected to the terminal through the EIA interface. In order to solve this problem, it has been proposed to replace the physical TC lead by logic information. However, this approach still raises the fundamental question: How does one communicate with a modem which is transparent? In other words, is it possible to find a message that is unique for all data link protocols which can be used on telephone lines, taking into account the fact that the modem does not know which protocol is used by the terminal? This article describes a bit string of 8 bytes which insures the uniqueness of an SDLC (synchronons data link control) message over the following data link controls: SDLC coded NRZI BSC coded EBCDIC BSC coded ASCII The uniqueness of the message over SDLC is insured by the address and control fields. The proposed character string is (in hexadecimal) 0/5 10/ 42 08 21 84 10 42. In the particular case of tailed modems, this leads to the following definition: 7E FD 1B 0/5 10/ 42 08 21 84 10 42 00 B...