[chan configure], a built-in Tcl command, sets and retrieves options for channels. It replaces the older [fconfigure].
Instruct Tcl to always send output to stdout immediately, whether or not it is to a terminal:
chan configure stdout -buffering none
Instruct Tcl to read pure bytes from a channel and write bytes to it, rather than characters:
chan configure $binaryDataFile -translation binary
LV 2008 Feb 28:
Some of the wiki pages talk about the construct,
chan configure $serial_port -mode "$baudRate,$plex,$bits,$polarity"
or some such thing. The -mode flag, used for specifying baud rate, etc, has moved to open now. I don't know how one would change those values on an open descriptor...