Try this:
1.Open two files at the beginning of your script
set fo [open simple-out1.tr w]
set f1 [open simple-out2.tr w]
2.in your record procedure, save data in the files like this
puts $f0 "$now [expr $bw0]"
puts $f1 "$now [expr $bw1]"
3.then call xgraph with this command:
"exec xgraph simple-out1.tr simple-out2.tr "
Don't forget to close the files before calling xgraph
Good luck
