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Article #14887Re: What are the threshold levels for RS-232?
From: Len Chisholm
Date: Mon, 14 Dec 1992 02:59
Date: Mon, 14 Dec 1992 02:59
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My computer ( a Toshiba T5200 portable ) and a number of our REAL IBM PC and AT serial cards have the bias pins on their RS232 inputs connected in such a fashion that they require a negative-going input to operate i.e. the lower hysteresis threshold is below zero. The clone/Taiwanese/etc. multi-function cards we have used seem to work on positive-going signals only. If you are building general purpose equipment you should emit negative- going signals to be sure - you may get the same problem from other BIG-NAME suppliers. -- ------------------------------------------------------------------------- | LEN CHISHOLM , Systems programmer | EMail: L.Chisholm@massey.ac.nz | | Department of Production Technology | Phone: +64 6 3505262 | | Massey University | FAX: +64 6 3505604 | | Palmerston North, New Zealand | | -------------------------------------------------------------------------
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Newsgroups: sci.electronics Path: arc1-ca.pugleaf.net!sparky!uunet!comp.vuw.ac.nz!cc-server4.massey.ac.nz!L.Chisholm From: L.Chisholm@massey.ac.nz (Len Chisholm) Subject: Re: What are the threshold levels for RS-232? Message-ID: <1992Dec14.025912.14282@massey.ac.nz> Summary: IBM and Toshiba equipment requiring negative-going RS232 signals Keywords: RS232 voltage Organization: Massey University, Palmerston North, New Zealand References: <widow.723866984@camelot> <JON_SREE.92Dec9075724@world.std.com> X-Reader: NETNEWS/PC Version 2c Date: Mon, 14 Dec 92 02:59:12 GMT Lines: 19