anonymous.FSOEP@his-phoenix-multics.arpa (JGuerber) (03/18/85)
A while ago, someone asked about break keys; here's how I've done it: Hook up a SPDT switch with - common on modem's pin 3 - normally closed on computer's pin 2 (TxD) (This would normally be connected to the modem's pin 3) - normally open on pin 20 (DTR) of both computer and modem. Depressing the switch will then pull the TxD line low for about 1/3 second, which is the standard break signal. I have had absolutely no problems from this set-up with my Franklin Ace 1200 and Rixon R212A modem.I understand that it may be wise to add resistors, but since I wasn't sure of the values I didn't; the electronics have survived thus far. Also, you may find it helpful to use a terminal block to make the connections, and use alligator-clip wires at first. A software method I have heard of but not tried is to send a few nulls with the baud rate turned down to about 5 or so. -- Jeff Guerber (JGuerber.FSOEP at HIS-PHOENIX-MULTICS)
dmt@ahutb.UUCP (d.m.tutelman) (03/20/85)
REFERENCES: <9297@brl-tgr.ARPA> > Hook up a SPDT switch with - common on modem's pin 3 - normally > closed on computer's pin 2 (TxD) (This would normally be connected to > the modem's pin 3) - normally open on pin 20 (DTR) of both computer and > modem. Nice! Neat, should work, and apparently does. > Depressing the switch will then pull the TxD line low for about 1/3 > second, which is the standard break signal. I think it's pulling the line high, not low. > A software method I have heard of but not tried is to send > a few nulls with the baud rate turned down to about 5 or so. A single null should be sufficient. A few might be confusing. Dave Tutelman