Add check for masspos when detecting data type

sohstationviewer/model/reftek_data/reftek_reader/log_file_reader.py

@@ -37,13 +37,19 @@ def detect_log_file_packet_format(packet: List[str]) -> LogFileFormat:
     # at the start of a packet, we know the log file is from SOHStationViewer.
     if packet_start.startswith('Events:'):
         return 'sohstationviewer'
+    # Unlike logpeek, we are writing the mass position in its own packet. So,
+    # a packet that starts with mass position data would be an SOHStationViewer
+    # packet.
+    if packet_start.startswith('LPMP'):
+        return 'sohstationviewer'
 
     # Logpeek write its events' info right after an SH packet.
     packet_end = packet[-1]
     packet_end_with_event_info = (packet_end.startswith('DAS') or
                                   packet_end.startswith('WARNING'))
-    if (packet_start.startswith('State of Health') and
-            packet_end_with_event_info):
+    packet_end_with_mass_pos = packet_end.startswith('LPMP')
+    packet_end_special = packet_end_with_event_info or packet_end_with_mass_pos
+    if packet_start.startswith('State of Health') and packet_end_special:
         return 'logpeek'