diff --git a/src/dnp3demo/__main__2.py b/src/dnp3demo/__main__2.py
index 26905f5..cb9dba8 100644
--- a/src/dnp3demo/__main__2.py
+++ b/src/dnp3demo/__main__2.py
@@ -5,6 +5,8 @@
     control_workflow_demo_master
 import argparse
 
+from dnp3demo import run_master
+
 
 def main():
 
@@ -15,18 +17,6 @@ def main():
         # epilog="Thanks for using %(prog)s! :)",
     )
 
-    # borrow children program arg parser
-    from dnp3demo import run_master
-    # parser = run_master.arg_config()
-
-    # p = argparse.ArgumentParser()
-    s = parser.add_subparsers()
-    ss = s.add_parser('script', parents=[parser], add_help=False)
-
-    print(f"====parser, {vars(parser.parse_args())}")
-    # print(f"====s, {vars(s.parse_args())}")
-    print(f"====ss, {vars(ss.parse_args())}")
-
     # Adding optional argument
     parser.add_argument("-d", "--duration", action="store",
                         help="Configure demo duration (in seconds.)",
@@ -34,11 +24,46 @@ def main():
                         default=60,
                         metavar="sec")
 
+    # use exclusive group, choose among scripts to run,
+    # by default run --demo-get-point
+
+    group = parser.add_mutually_exclusive_group(required=False)
+    group.description = "some description"
+    group.add_argument("-rm", "--run-master-station", action="store_true",
+                       help="Run a standalone master station.", )
+    group.add_argument("-ro", "--run-outstation", action="store_true",
+                       help="Run a standalone master station.")
+    group.add_argument("-dg", "--demo-get-point", action="store_true",
+                       help="Demo get point workflow.")
+    group.add_argument("-ds", "--demo-set-point", action="store_true",
+                       help="Demo set point workflow.")
+    group.add_argument("-rim", "--run-interactive-master", action="store_true",
+                       help="Run an interactive master station. (For set point demo)")
+
+    # subcommand
+    # Note: by using `dest="command"`, we create namespace, such that args.command
+    # to access subcommand
+    subparsers = parser.add_subparsers(title="Run Station Sub-command",
+                                       help='run-station sub-command help',
+                                       dest="command")
+    parser_master = subparsers.add_parser('master', help='run an interactive master')
+    # parser_master = subparsers
+    parser_master = run_master.setup_args(parser_master)
+    # hacky: added subcommands
+    # parser_master.add_argument("")
+
     args = parser.parse_args()
-    print(f"1st d_args, {vars(args)}")
+    # args_master = parser_master.parse_args()
+    print(f"1st d_args args, {vars(args)}")
+    # print(f"1st d_args args_master, {vars(args_master)}")
 
-    from dnp3demo import run_master
-    run_master.main(sys.argv)
+    # parser.set_defaults(func=run_master.main, which="master")
+    # run_master.main()
+    cmd = args.command
+    if cmd == "master":
+        run_master.main(parser=parser)
+        pass
+    # print(f"===========cmd {cmd}")
 
 
 if __name__ == "__main__":
diff --git a/src/dnp3demo/run_master.py b/src/dnp3demo/run_master.py
index cad55ff..d74c7cd 100644
--- a/src/dnp3demo/run_master.py
+++ b/src/dnp3demo/run_master.py
@@ -21,13 +21,7 @@
 _log.setLevel(logging.DEBUG)
 
 
-def arg_config() -> argparse.ArgumentParser:
-    # Initialize parser
-    parser = argparse.ArgumentParser(
-        prog="dnp3-master",
-        description="Run a dnp3 master",
-        # epilog="Thanks for using %(prog)s! :)",
-    )
+def setup_args(parser: argparse.ArgumentParser) -> argparse.ArgumentParser:
 
     # Adding optional argument
     parser.add_argument("-mip", "--master-ip", action="store", default="0.0.0.0", type=str,
@@ -41,21 +35,26 @@ def arg_config() -> argparse.ArgumentParser:
     parser.add_argument("-oid", "--outstation-id", action="store", default=2, type=int,
                         metavar="<ID>")
 
-    # # Read arguments from command line
-    # args = parser.parse_args()
-
-    # choose among the following scripts to run
     return parser
 
 
-def main(*args, **kwargs):
+def main(parser=None, *args, **kwargs):
+
+    if parser is None:
+        # Initialize parser
+        parser = argparse.ArgumentParser(
+            prog="dnp3-master",
+            description="Run a dnp3 master",
+            # epilog="Thanks for using %(prog)s! :)",
+        )
+        parser = setup_args(parser)
+
     # Read arguments from command line
-    parser = arg_config()
     args = parser.parse_args()
 
-    # or use dict
+    # dict to store args.Namespace
     d_args = vars(args)
-    print(d_args)
+    print(__name__, d_args)
 
     master_application = MyMasterNew(
         masterstation_ip_str=args.master_ip,