Serial Ports on Windows

I created this page in case some people may have some questions or 
answers about [using a serial port] on Windows.

I just tried to communicate with com1 on a Windows 2000 machine.  
For some reason I could not receive any data using the following commands in Wish.

   % proc rd_chid {chid} {
   set msg [gets $chid]
   puts $msg
   }
   % set com [open com1: r+]
   % fconfigure $com -mode 9600,n,8,1 -blocking 0 -translation auto -buffering line
   % fileevent $com readable [list rd_chid $com]

However, I was able to receive data by putting those last 3 lines into its own procedure...

   % proc rd_chid {chid} {
   set msg [gets $chid]
   puts $msg
   }
   % proc open_com {} {
   global com
   set com [open com1: r+]
   fconfigure $com -mode 9600,n,8,1 -blocking 0 -translation auto -buffering line
   fileevent $com readable [list rd_chid $com]
   }
   % open_com
   # lots of data comes streaming :)
   % close $com
jg

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Tcl 8.4 greatly improved serial port control across platforms.  
Refer to the updated [fconfigure] documentation for more info.

----
To retrieve details on input/output errors--which are, 
in general, frequent, when working with serial lines--interrogate
    set details [fconfigure $serial_handle -lasterror]
8.3.4 introduced this capability.

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How can I connect to a com port higher than 9?
(I am using a terminal server, and its driver creates com ports upto 16 or so.)
Would appreciate answer by mail - anner@flexlight-networks.com

Thanks

25Aug2003 [PS]: You need to use the 'generic' name (I think it is actually the UNC path) 
of the com port. Use the file name \\.\com13 to open 'com13:' 
Mind you, windows wants to see those all those \ chars, so use [[open \\\\.\\com13 r+]]. 
I have not tested this myself... E_NO_ACCESS_TO_BIG_SERIAL_CARD. But it does work :)
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The following code will enumerate the serial devices 
on a windows XP machine - including USB devices.

 package require registry
 
 proc get_serial_ports { } {
    set serial_base "HKEY_LOCAL_MACHINE\\HARDWARE\\DEVICEMAP\\SERIALCOMM"
    set values [ registry values $serial_base ]
 
    set result {}
 
    foreach valueName $values {
       lappend result [ registry get $serial_base $valueName ]
    }
 
    return $result
 }

----
Also note that you want:

 set serial [open "COM1:" "RDWR"]

and not

 set serial [open "COM1" "RDWR"]

without that colon (:), you get a file in the current directory called COM1.
Also, note that you will most frequently see code something like this:

 set serial [open "COM1:" "RDWR"]
 fconfigure $serial -mode 9600,n,8,1

where fconfigure sets the baud rate, etc. of the serial port.


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[Category Device Control] - [Category Windows]