diff --git a/macros/setRTS.sci b/macros/setRTS.sci
new file mode 100644
index 0000000..003b874
--- /dev/null
+++ b/macros/setRTS.sci
@@ -0,0 +1,9 @@
+function result=setRTS(h,rts)
+// ------------------------------------------------------
+// Function to set the RTS-flag
+// h - handle of serial port
+// rts - 0 (off), 1 (on)
+//---------------------------------------------------------------//
+   TCL_EvalStr("fconfigure "+h+" -ttycontrol  [list  RTS "+rts+"]")
+   result=1;
+endfunction