diff --git a/hl7parser/hl7_data_types.py b/hl7parser/hl7_data_types.py
index 2a8ba81..6969871 100644
--- a/hl7parser/hl7_data_types.py
+++ b/hl7parser/hl7_data_types.py
@@ -168,12 +168,22 @@ class HL7Datetime(HL7DataType):
     """
         HL7 datetime data type
 
+        Complete Supports the DTM format and only partial support for the older TM format,
+        which is deprecated since hl7 2.6.
+        If the datetime is given in TM format the second component is ignored, because its not
+        reliable and the first component is treated like the DTM formatted datetime.
+
         example input:
             198808181126
     """
     component_map = ['datetime']
 
-    def __init__(self, composite, delimiter, use_delimiter="subcomponent_separator"):
+    def __init__(self, composite, delimiters, use_delimiter="component_separator"):
+
+        delimiter = getattr(delimiters, use_delimiter)
+        composite = composite.split(delimiter)
+        composite = composite[0]
+
         if len(composite) == 0:
             self.datetime = ""
             self.isNull = True

diff --git a/tests/data_types.py b/tests/data_types.py
index d5afa72..97e0d16 100644
--- a/tests/data_types.py
+++ b/tests/data_types.py
@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 import pytest
 
+from hl7parser.hl7 import HL7Delimiters
 from hl7parser.hl7_data_types import HL7Datetime
 
 
@@ -13,9 +14,12 @@ from hl7parser.hl7_data_types import HL7Datetime
         ("", "", ""),
         ("2010", "2010-01-01T00:00:00", "2010"),
         ("-200", "", ""),
+        ("20190924143134^YYYYMMDDHHMMSS", "2019-09-24T14:31:34", "20190924143134")
     ]
 )
 def test_datetime(input_string, isoformat, string_repr):
-    dt = HL7Datetime(input_string, "|")
+
+    delimiters = HL7Delimiters(*"|^~\&")
+    dt = HL7Datetime(input_string, delimiters)
     assert dt.isoformat() == isoformat
     assert str(dt) == string_repr
diff --git a/tests/test_parse.py b/tests/test_parse.py
index 9ed57c6..82163da 100644
--- a/tests/test_parse.py
+++ b/tests/test_parse.py
@@ -10,6 +10,8 @@ import unittest
 import six
 import sys
 import pytest
+import datetime
+
 
 @pytest.mark.skipif(sys.version_info.major > 2, reason="not relevant for python 3")
 def test_bytestring_segment():
@@ -241,7 +243,8 @@ class TestParsing(unittest.TestCase):
 
     def test_pv1_segment(self):
         segment = HL7Segment(
-            "PV1|1|I|2000^2012^01||||004777^ATTEND^AARON^A|||SUR||||ADM|A0|"
+            "PV1|1|I|2000^2012^01||123^^^^^^20190924143134&YYYYMMDDHHMMSS"
+            "||004777^ATTEND^AARON^A|||SUR||||ADM|A0|"
         )
 
         self.assertEqual(six.text_type(segment.patient_class), "I")
@@ -266,6 +269,9 @@ class TestParsing(unittest.TestCase):
         self.assertEqual(
             six.text_type(segment.hospital_service), "SUR")
 
+        self.assertEqual(
+            six.text_type(segment.preadmit_number.effective_date.datetime), "2019-09-24 14:31:34")
+
 
 def test_in1_segment():
     message_data = (

HL7 Datetime fails to parse DTM with precision filed
If the optional precision at the DTM data filed is not empty, the given datetime (DTM) can not be parsed,instead a ValueError is raised.

***Example hl7 message to reproduce the error:***

```
MSH|^~\&|||||||ADT^A01|12346789|P|2.7|
EVN|A01|20190924143134^YYYYMMDDHHMMSS||
PID|||59wrtt0w9suJ-^foo^bar||Hilde^Held||19660119|F|||||||||||||
PV1||0|7697^69^^MED2||||||||||||||||744784|||||||||||||||||||||||||20190916143134920350||
IN1|1||00818903|TKK||||4||||||||||||||||||||||||||||00597522|
```
tests/data_types.py::test_datetime[20190924143134^YYYYMMDDHHMMSS-2019-09-24T14:31:34-20190924143134] tests/test_parse.py::TestParsing::test_pv1_segment
tests/data_types.py::test_datetime[198808181126-1988-08-18T11:26:00-198808181126] tests/data_types.py::test_datetime[--] tests/data_types.py::test_datetime[2010-2010-01-01T00:00:00-2010] tests/data_types.py::test_datetime[-200--] tests/test_parse.py::TestParsing::test_address tests/test_parse.py::TestParsing::test_datetime tests/test_parse.py::TestParsing::test_len tests/test_parse.py::TestParsing::test_message_parse tests/test_parse.py::TestParsing::test_mrg_message_parse tests/test_parse.py::TestParsing::test_multiple_segments_parse tests/test_parse.py::TestParsing::test_non_zero tests/test_parse.py::TestParsing::test_simple_segments_parse tests/test_parse.py::TestParsing::test_successful_query_status tests/test_parse.py::TestParsing::test_trailing_segment_fields tests/test_parse.py::TestParsing::test_unknown_message_parse tests/test_parse.py::TestParsing::test_unsuccessful_query_status tests/test_parse.py::test_in1_segment