diff --git a/app/src/gen3plus/solarman_v5.py b/app/src/gen3plus/solarman_v5.py
index 5c8e588..fe1e347 100644
--- a/app/src/gen3plus/solarman_v5.py
+++ b/app/src/gen3plus/solarman_v5.py
@@ -186,12 +186,12 @@ class SolarmanV5(Message):
             type += 'S'
         return switch.get(type, '???')
 
-    def _timestamp(self):   # pragma: no cover
+    def _timestamp(self):
         # utc as epoche
-        return int(time.time())
+        return int(time.time())    # pragma: no cover
 
     def _heartbeat(self) -> int:
-        return 60
+        return 60                  # pragma: no cover
 
     def __parse_header(self, buf: bytes, buf_len: int) -> None:
 
diff --git a/app/src/messages.py b/app/src/messages.py
index 9f6efdf..5bcf711 100644
--- a/app/src/messages.py
+++ b/app/src/messages.py
@@ -76,7 +76,7 @@ class Message(metaclass=IterRegistry):
 
     def _update_header(self, _forward_buffer):
         '''callback for updating the header of the forward buffer'''
-        return
+        return  # pragma: no cover
 
     '''
     Our puplic methods
diff --git a/app/tests/test_solarman.py b/app/tests/test_solarman.py
index 28af3ea..0f54f0c 100644
--- a/app/tests/test_solarman.py
+++ b/app/tests/test_solarman.py
@@ -325,6 +325,54 @@ def UnknownMsg():  # 0x5110
     msg += b'\x15'
     return msg
 
+@pytest.fixture
+def SyncStartIndMsg():  # 0x4310
+    msg  = b'\xa5\x2f\x00\x10\x43\x0c\x0d' +get_sn()  +b'\x81\x7a\x0b\x2e\x32'
+    msg += b'\x39\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x41\x6c\x6c\x69\x75\x73'
+    msg += b'\x2d\x48\x6f\x6d\x65\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+    msg += b'\x00\x00\x00\x00\x00\x00\x00\x00\x61\x01'
+    msg += correct_checksum(msg)
+    msg += b'\x15'
+    return msg
+
+@pytest.fixture
+def SyncStartRspMsg():  # 0x1310
+    msg  = b'\xa5\x0a\x00\x10\x13\x0d\x0d' +get_sn()  +b'\x81\x01'
+    msg += total()  
+    msg += hb()
+    msg += correct_checksum(msg)
+    msg += b'\x15'
+    return msg
+
+@pytest.fixture
+def SyncStartFwdMsg():  # 0x4310
+    msg  = b'\xa5\x2f\x00\x10\x43\x0e\x0d' +get_sn()  +b'\x81\x7a\x0b\x2e\x32'
+    msg += b'\x39\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x41\x6c\x6c\x69\x75\x73'
+    msg += b'\x2d\x48\x6f\x6d\x65\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+    msg += b'\x00\x00\x00\x00\x00\x00\x00\x00\x61\x01'
+    msg += correct_checksum(msg)
+    msg += b'\x15'
+    return msg
+
+
+@pytest.fixture
+def AtCommandIndMsg():  # 0x4510
+    msg  = b'\xa5\x27\x00\x10\x45\x02\x01' +get_sn() +b'\x01\x02\x00'
+    msg += b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'           
+    msg += b'AT+TIME=214028,1,60,120\r'
+    msg += correct_checksum(msg)
+    msg += b'\x15'
+    return msg
+
+@pytest.fixture
+def AtCommandRspMsg():  # 0x1510
+    msg  = b'\xa5\x0a\x00\x10\x15\x02\x02' +get_sn()  +b'\x01\x01'
+    msg += total()  
+    msg += hb()
+    msg += correct_checksum(msg)
+    msg += b'\x15'
+    return msg
+
 @pytest.fixture
 def HeartbeatIndMsg():  # 0x4710
     msg  = b'\xa5\x01\x00\x10\x47\x10\x84' +get_sn()
@@ -343,17 +391,19 @@ def HeartbeatRspMsg():  # 0x1710
     return msg
 
 @pytest.fixture
-def AtCommandIndMsg():  # 0x4510
-    msg  = b'\xa5\x27\x00\x10\x45\x02\x01' +get_sn() +b'\x01\x02\x00'
-    msg += b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'           
-    msg += b'AT+TIME=214028,1,60,120\r'
+def SyncEndIndMsg():  # 0x4810
+    msg  = b'\xa5\x3c\x00\x10\x48\x06\x07' +get_sn() +b'\x01\xa5\x3c\x2e\x32'
+    msg += b'\x2c\x00\x00\x00\xc1\x01\xec\x33\x01\x05\x2c\xff\xff\xff\xff\xff'
+    msg += b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'
+    msg += b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'
+    msg += b'\xff\xff\xff\xff\xff\xff\xff'
     msg += correct_checksum(msg)
     msg += b'\x15'
     return msg
 
 @pytest.fixture
-def AtCommandRspMsg():  # 0x1510
-    msg  = b'\xa5\x0a\x00\x10\x15\x03\x01' +get_sn()  +b'\x01\x01'
+def SyncEndRspMsg():  # 0x1810
+    msg  = b'\xa5\x0a\x00\x10\x18\x07\x07' +get_sn()  +b'\x01\x01'
     msg += total()  
     msg += hb()
     msg += correct_checksum(msg)
@@ -733,9 +783,86 @@ def test_heartbeat_rsp(ConfigTsunInv1, HeartbeatRspMsg):
     assert m.db.stat['proxy']['Invalid_Msg_Format'] == 0
     m.close()
 
+def test_sync_start_ind(ConfigTsunInv1, SyncStartIndMsg, SyncStartRspMsg, SyncStartFwdMsg):
+    ConfigTsunInv1
+    m = MemoryStream(SyncStartIndMsg, (0,))
+    m.read()         # read complete msg, and dispatch msg
+    assert not m.header_valid  # must be invalid, since msg was handled and buffer flushed
+    assert m.msg_count == 1
+    assert m.header_len==11
+    assert m.snr == 2070233889
+    # assert m.unique_id == '2070233889'
+    assert m.control == 0x4310
+    assert str(m.seq) == '0d:0d'  # value after sending response
+    assert m.data_len == 47
+    assert m._recv_buffer==b''
+    assert m._send_buffer==SyncStartRspMsg
+    assert m._forward_buffer==SyncStartIndMsg
+    assert m.db.stat['proxy']['Invalid_Msg_Format'] == 0
+
+    m._update_header(m._forward_buffer)
+    assert str(m.seq) == '0d:0e'  # value after forwarding indication
+    assert m._forward_buffer==SyncStartFwdMsg
+
+    m.close()
+
+def test_sync_start_rsp(ConfigTsunInv1, SyncStartRspMsg):
+    ConfigTsunInv1
+    m = MemoryStream(SyncStartRspMsg, (0,), False)
+    m.read()         # read complete msg, and dispatch msg
+    assert not m.header_valid  # must be invalid, since msg was handled and buffer flushed
+    assert m.msg_count == 1
+    assert m.header_len==11
+    assert m.snr == 2070233889
+    assert m.unique_id == '2070233889'
+    assert m.control == 0x1310
+    assert str(m.seq) == '0d:0d'  # value after sending response
+    assert m.data_len == 0x0a
+    assert m._recv_buffer==b''
+    assert m._send_buffer==b''
+    assert m._forward_buffer==b''  # HeartbeatRspMsg
+    assert m.db.stat['proxy']['Invalid_Msg_Format'] == 0
+    m.close()
+
+def test_sync_end_ind(ConfigTsunInv1, SyncEndIndMsg, SyncEndRspMsg):
+    ConfigTsunInv1
+    m = MemoryStream(SyncEndIndMsg, (0,))
+    m.read()         # read complete msg, and dispatch msg
+    assert not m.header_valid  # must be invalid, since msg was handled and buffer flushed
+    assert m.msg_count == 1
+    assert m.header_len==11
+    assert m.snr == 2070233889
+    # assert m.unique_id == '2070233889'
+    assert m.control == 0x4810
+    assert str(m.seq) == '07:07'  # value after sending response
+    assert m.data_len == 60
+    assert m._recv_buffer==b''
+    assert m._send_buffer==SyncEndRspMsg
+    assert m._forward_buffer==SyncEndIndMsg
+    assert m.db.stat['proxy']['Invalid_Msg_Format'] == 0
+    m.close()
+
+def test_sync_end_rsp(ConfigTsunInv1, SyncEndRspMsg):
+    ConfigTsunInv1
+    m = MemoryStream(SyncEndRspMsg, (0,), False)
+    m.read()         # read complete msg, and dispatch msg
+    assert not m.header_valid  # must be invalid, since msg was handled and buffer flushed
+    assert m.msg_count == 1
+    assert m.header_len==11
+    assert m.snr == 2070233889
+    assert m.unique_id == '2070233889'
+    assert m.control == 0x1810
+    assert str(m.seq) == '07:07'  # value after sending response
+    assert m.data_len == 0x0a
+    assert m._recv_buffer==b''
+    assert m._send_buffer==b''
+    assert m._forward_buffer==b''  # HeartbeatRspMsg
+    assert m.db.stat['proxy']['Invalid_Msg_Format'] == 0
+    m.close()
+
 def test_at_command_ind(ConfigTsunInv1, AtCommandIndMsg, AtCommandRspMsg):
     ConfigTsunInv1
-    m = MemoryStream(AtCommandIndMsg, (0,))
+    m = MemoryStream(AtCommandIndMsg, (0,), False)
     m.read()         # read complete msg, and dispatch msg
     assert not m.header_valid  # must be invalid, since msg was handled and buffer flushed
     assert m.msg_count == 1
@@ -743,7 +870,7 @@ def test_at_command_ind(ConfigTsunInv1, AtCommandIndMsg, AtCommandRspMsg):
     assert m.snr == 2070233889
     # assert m.unique_id == '2070233889'
     assert m.control == 0x4510
-    assert str(m.seq) == '01:03'
+    assert str(m.seq) == '02:02'
     assert m.data_len == 39
     assert m._recv_buffer==b''
     assert m._send_buffer==AtCommandRspMsg
@@ -817,15 +944,19 @@ def test_build_logger_modell(ConfigTsunAllowAll, DeviceIndMsg):
 
 def test_AT_cmd(ConfigTsunAllowAll, DeviceIndMsg, DeviceRspMsg, AtCommandIndMsg):
     ConfigTsunAllowAll
-    m = MemoryStream(DeviceIndMsg)
+    m = MemoryStream(DeviceIndMsg, (0,), True)
     m.read()
+    assert m.control == 0x4110
+    assert str(m.seq) == '01:01'
     assert m._recv_buffer==b''
     assert m._send_buffer==DeviceRspMsg
     assert m._forward_buffer==DeviceIndMsg
+    
     m._send_buffer = bytearray(0) # clear send buffer for next test    
     m._forward_buffer = bytearray(0) # clear send buffer for next test    
     m.send_at_cmd('AT+TIME=214028,1,60,120')
     assert m._recv_buffer==b''
     assert m._send_buffer==AtCommandIndMsg
     assert m._forward_buffer==b''
+    assert str(m.seq) == '01:02'
     m.close()