davison@bnl.UUCP (daniel burton davison) (12/11/84)
I have a system at home which cannot generate a "break" signal. I have asked various random people more knowledgeable in electronics than I about what exactly a "break" is. I was told: (1) the DTR (data terminal ready) line going to ground for 300+/- 200 msec; (2) the XMT (Transmit Data) line going to ground for 500msec. I wired up a small switch on both the TD line and DTR line, but neither generated a "break" at the test systems (a Univac and a Unix). So, I'm appealing to the net: is there some cheep minor hardware trick that will allow me to generate a "break" signal? This is vital since the systems I usually use *absolutely* require a "break". I only have one part of my home system which can generate a "break"--an atari 800 with the TELELINK program in ROM. Any and all replies will be welcome and if there is any interest I'm summarize to the net. Thanks, dan davison davison@bnl.arpa ...decvax!philabs!sbcs!bnl!davison [please use arpa if possible since uucp is behaving very erratically at bnl]
dave@rocksvax.UUCP (12/17/84)
Break is taking the TD (transmit data) line from (-15 -> -3) Volts
(Ground sometimes works but is not really a valid RS-232 voltage level)
to (+3 -> +15) Volts for some number of 100 mS. Generally all you need
to do is keep the TD high long enough to make a framing error occur in
the UART device. Worked for me any time I needed a break.
Dave
arpa: Sewhuk.HENR@Xerox.ARPA
uucp: {allegra,rochester,amd,sunybcs}!rocksvax!dave