Serial Port In and Out Detection
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From: Keith on 6 Mar 2010 05:34 If I attempt to open a serial port and the device exist: com1: or /dev/ttyS1 but does not respond TCL/TK will lock up waiting for the device to respond Is there a way to test a serial port connection so that tcl/tk will not lock up if the device exists but does not respond? -- Best Regards, Keith http://home.comcast.net/~kilowattradio/ Tired of Google Groups? http://home.comcast.net/~kilowattradio/usenet.html
From: James Littlefield on 6 Mar 2010 08:49 Keith wrote: > If I attempt to open a serial port and the device exist: > com1: or /dev/ttyS1 > but does not respond TCL/TK will lock up waiting for the device to respond > Is there a way to test a serial port connection so that tcl/tk will not > lock up if the device exists but does not respond? > > > Not sure if you are saying that the open succeeds but attempting to read from the device locks up? If so, you can do any of several things.... - "fconfigure" the file as non-blocking. This will allow you to do a gets w/o getting stuck if there is nothing to be read - You might also take a look at the event driven I/O manpages and the "fileevent" command --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Joerg H on 6 Mar 2010 14:11 Keith wrote: > If I attempt to open a serial port and the device exist: > com1: or /dev/ttyS1 > but does not respond TCL/TK will lock up waiting for the device to respond > Is there a way to test a serial port connection so that tcl/tk will not > lock up if the device exists but does not respond? > > > I have done this many times in a separate procedure: .... set fileid [open "/dev/ttyS0" w+] fconfigure $fileid -buffering line -blocking no .... puts "*IDN?" flush $fileid set end [expr [clock clicks -milliseconds] + 1000] while {[clock clicks -milliseconds] < $end} { gets $fileid returnval if { [fblocked $fileid] == 0 } { return $returnVal } } return -1 This code waits one second if the devices answers and returns $returnVal. if not it returns -1. I use it for control measurement devices such as dmm's or scopes. So the program doesn't stop if I have'nt switched on the devices. Joerg
From: Keith on 6 Mar 2010 14:45
On Sat, 06 Mar 2010 20:11:55 +0100, Joerg H <joerg.honerla(a)t-online.de> wrote: > > puts "*IDN?" > flush $fileid Is the puts going to stdout or someplace else? -- Best Regards, Keith http://home.comcast.net/~kilowattradio/ Tired of Google Groups? http://home.comcast.net/~kilowattradio/usenet.html |