diff --git a/S7.Net.UnitTest/S7.Net.UnitTest.csproj b/S7.Net.UnitTest/S7.Net.UnitTest.csproj
index d65a804..cbe6c47 100644
--- a/S7.Net.UnitTest/S7.Net.UnitTest.csproj
+++ b/S7.Net.UnitTest/S7.Net.UnitTest.csproj
@@ -79,6 +79,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Helpers\TestLongStruct.cs" />
     <Compile Include="TypeTests\StringExTests.cs" />
+    <Compile Include="TypeTests\StringTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="snap7.dll">
diff --git a/S7.Net.UnitTest/TypeTests/StringTests.cs b/S7.Net.UnitTest/TypeTests/StringTests.cs
new file mode 100644
index 0000000..15a528b
--- /dev/null
+++ b/S7.Net.UnitTest/TypeTests/StringTests.cs
@@ -0,0 +1,85 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class StringTests
+    {
+        [TestMethod]
+        public void WriteNullWIthReservedLengthZero()
+        {
+            AssertToByteArrayEquals(null, 0);
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthZero()
+        {
+            AssertToByteArrayEquals("", 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthZero()
+        {
+            AssertToByteArrayEquals("A", 0);
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals(null, 1, 0);
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("", 1, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("A", 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthTwo()
+        {
+            AssertToByteArrayEquals("A", 2, (byte) 'A', 0);
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("Abc", 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthTwo()
+        {
+            AssertToByteArrayEquals("Abc", 2, (byte) 'A', (byte) 'b');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthThree()
+        {
+            AssertToByteArrayEquals("Abc", 3, (byte) 'A', (byte) 'b', (byte) 'c');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthFour()
+        {
+            AssertToByteArrayEquals("Abc", 4, (byte) 'A', (byte) 'b', (byte) 'c', 0);
+        }
+
+        private static void AssertFromByteArrayEquals(string expected, params byte[] bytes)
+        {
+            Assert.AreEqual(expected, String.FromByteArray(bytes));
+        }
+
+        private static void AssertToByteArrayEquals(string value, int reservedLength, params byte[] expected)
+        {
+            CollectionAssert.AreEqual(expected, String.ToByteArray(value, reservedLength));
+        }
+    }
+}