diff --git a/test/test_client_multidrop.py b/test/test_client_multidrop.py
new file mode 100644
index 000000000..946b43138
--- /dev/null
+++ b/test/test_client_multidrop.py
@@ -0,0 +1,120 @@
+"""Test server working as slave on a multidrop RS485 line."""
+from unittest import mock
+
+import pytest
+
+from pymodbus.framer.rtu_framer import ModbusRtuFramer
+from pymodbus.server.async_io import ServerDecoder
+
+
+class TestMultidrop:
+    """Test that server works on a multidrop line."""
+
+    slaves = [2]
+
+    good_frame = b"\x02\x03\x00\x01\x00}\xd4\x18"
+
+    @pytest.fixture(name="framer")
+    def _framer(self):
+        """Prepare framer."""
+        return ModbusRtuFramer(ServerDecoder())
+
+    @pytest.fixture(name="callback")
+    def _callback(self):
+        """Prepare dummy callback."""
+        return mock.Mock()
+
+    def test_ok_frame(self, framer, callback):
+        """Test ok frame."""
+        serial_event = self.good_frame
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_called_once()
+
+    def test_bad_crc(self, framer, callback):
+        """Test bad crc."""
+        serial_event = b"\x02\x03\x00\x01\x00}\xd4\x19"  # Manually mangled crc
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_not_called()
+
+    def test_wrong_unit(self, framer, callback):
+        """Test frame wrong unit"""
+        serial_event = (
+            b"\x01\x03\x00\x01\x00}\xd4+"  # Frame with good CRC but other unit id
+        )
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_not_called()
+
+    def test_big_split_response_frame_from_other_unit(self, framer, callback):
+        """Test split response."""
+        # This is a single *response* from device id 1 after being queried for 125 holding register values
+        # Because the response is so long it spans several serial events
+        serial_events = [
+            b"\x01\x03\xfa\xc4y\xc0\x00\xc4y\xc0\x00\xc4y\xc0\x00\xc4y\xc0\x00\xc4y\xc0\x00Dz\x00\x00C\x96\x00\x00",
+            b"?\x05\x1e\xb8DH\x00\x00D\x96\x00\x00D\xfa\x00\x00DH\x00\x00D\x96\x00\x00D\xfa\x00\x00DH\x00",
+            b"\x00D\x96\x00\x00D\xfa\x00\x00B\x96\x00\x00B\xb4\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
+            b"\x00\x00\x00\x00\x00\x00\x00N,",
+        ]
+        for serial_event in serial_events:
+            framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_not_called()
+
+    def test_split_frame(self, framer, callback):
+        """Test split frame."""
+        serial_events = [self.good_frame[:5], self.good_frame[5:]]
+        for serial_event in serial_events:
+            framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_called_once()
+
+    @pytest.mark.skip
+    def test_complete_frame_trailing_data_without_unit_id(self, framer, callback):
+        """Test trailing data."""
+        garbage = b"\x05\x04\x03"  # Note the garbage doesn't contain our unit id
+        serial_event = garbage + self.good_frame
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_called_once()
+
+    @pytest.mark.skip
+    def test_complete_frame_trailing_data_with_unit_id(self, framer, callback):
+        """Test trailing data."""
+        garbage = (
+            b"\x05\x04\x03\x02\x01\x00"  # Note the garbage does contain our unit id
+        )
+        serial_event = garbage + self.good_frame
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_called_once()
+
+    @pytest.mark.skip
+    def test_split_frame_trailing_data_with_unit_id(self, framer, callback):
+        """Test split frame."""
+        garbage = b"\x05\x04\x03\x02\x01\x00"
+        serial_events = [garbage + self.good_frame[:5], self.good_frame[5:]]
+        for serial_event in serial_events:
+            framer.processIncomingPacket(serial_event, callback, self.slaves)
+        callback.assert_called_once()
+
+    def test_wrapped_frame(self, framer, callback):
+        """Test wrapped frame."""
+        garbage = b"\x05\x04\x03\x02\x01\x00"
+        serial_event = garbage + self.good_frame + garbage
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+
+        # We probably should not respond in this case; in this case we've likely become desynchronized
+        # i.e. this probably represents a case where a command came for us, but we didn't get
+        # to the serial buffer in time (some other co-routine or perhaps a block on the USB bus)
+        # and the master moved on and queried another device
+        callback.assert_not_called()
+
+    @pytest.mark.skip
+    def test_frame_with_trailing_data(self, framer, callback):
+        """Test trailing data."""
+        garbage = b"\x05\x04\x03\x02\x01\x00"
+        serial_event = self.good_frame + garbage
+        framer.processIncomingPacket(serial_event, callback, self.slaves)
+
+        # We should not respond in this case for identical reasons as test_wrapped_frame
+        callback.assert_not_called()