Date: Tue, 17 Feb 1998 08:15:18 -0800 From: Don Wilde <don@partsnow.com> To: "Alex N. Zhuravlev" <alx@scn.ru> Cc: questions@FreeBSD.ORG Subject: Re: I need a device which can signalize the connection lost Message-ID: <34E9B796.DC9E5BEA@partsnow.com> References: <199802170609.NAA27582@keep.scn.ru>
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> You see ... It must be a remote device.And a person who can only understand that if > the light is on all OK and if off then he must call administrator. That's all. > I saw a neat tip in Electronic Design a while ago. You have a free serial port on your machine? After your ping script reports failure, have it toggle one of the free bits in the serial port, like DTR or CTS. On the other end of that bit, have a red-green (or red-white) bi-color LED plus a resistor tied to ground. You'll have to experiment, because line loss in the cable to your 'remote device' will reduce the voltage, but all you need is the LED, two wires and a resistor. In a nutshell, toggling a serial bit causes the output pin to toggle between + and - 12 volts DC with respect to pin 7 common ground. You could even just use TX and send data out the port at a low baud rate. This will give you red-green flashing. You know, this really is almost just $0.02 worth :) -- oooOOO O O O o * * * * * * o ___ _________ _________ ________ _________ _________ ___==_ V_=_=_DW ===--- Don Wilde [don@PartsNow.com] [http://www.PartsNow.com ] /oo0000oo-oo--oo-ooo---ooo-ooo---ooo-ooo--ooo-ooo---ooo-ooo---ooo-oo--oo To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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