Transmitting data on rs232 pins using tcl language

Thread Starter


Joined May 2, 2010
Hi all,

I am trying to transmit data on some rs232 pins but what I have is not working and google doesn't bring a lot of help.

I have tried the following command to turn on DTR:

set com6 [open com6: r+]
fconfigure $com_chid -ttycontrol {DTR 0}

This gives me an error " can't read "com_chid": no such variable"

Any ideas on how to do this or point me to a good, understandable source please?

Thank you in advance


Joined Jul 18, 2013
Do you actually need hardware handshaking in the application?
For most RS232 communications now, hardware handshake is not needed due to the speed of processing each end and the requirement to wait for a device to turn on a DTE device is not an issue.
If handshake IS needed, there is the software XON/XOFF method.
In this case, the hardware pins are jumpered each end, if necessary.
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Joined Feb 8, 2018
I know absolutely nothing about tcl, but when you get an error message that says there is no such variable it generally means the variable has not been declared. If the variable is supposed to be "built-in" in some fashion, this often means that some sort of header block has not been included.