Changes the DTR(Data Terminal Ready) status of Tera Term. (version 4.59 or later)
If the connection is not serial connection or flow control is not "none", this command will do nothing.
If <echo flag> is zero, the DTR is turned off.
If <echo flag> is non-zero, the DTR is turned on.
; DTR on setdtr 1 ; DTR off setdtr 0