Add simple asyncio RTU serial client exmaple

scripts/examples/simple_asyncio_rtu_client.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+# scripts/example/simple_async_rtu_client.py
+import asyncio
+
+from serial_asyncio import open_serial_connection
+
+from umodbus.client.serial import rtu
+
+
+async def main():
+ reader, writer = await open_serial_connection(url='/dev/ttyS1', timeout=1)
+
+ # Returns a message or Application Data Unit (ADU) specific for doing
+ # Modbus TCP/IP.
+ message = tcp.write_multiple_coils(slave_id=1, starting_address=1, values=[1, 0, 1, 1])
+
+ # Response depends on Modbus function code. This particular returns the
+ # amount of coils written, in this case it is.
+ response = await tcp.async_send_message(message, reader, writer)
+
+ writer.close()
+ await writer.wait_closed()
+
+
+asyncio.run(main())