diff --git a/README.md b/README.md
index 5f7cf96..aa9735a 100644
--- a/README.md
+++ b/README.md
@@ -44,14 +44,6 @@ END_NAMESPACE
 |-|-|-|
 |NONE       | Integer.ToString(value := 123) | '123'
 |FORCE_SIGN | Integer.ToString(value := 123, mode := ConversionMode#FORCE_SIGN) | '+123'
-<!-- |FORCE_LEADING_ZEROS | Integer.ToString(value := INT#123)  | '+00123'
-|FORCE_LEADING_ZEROS | Integer.ToString(value := DINT#123) | '+0000000123'  -->
-
-<!-- > Modes can be combined. Example:
-> ```
-> Integer.ToString(value := 123, mode := ConversionMode#FORCE_SIGN)
-> ```
->  -->
 
 ## Functions
 
@@ -167,6 +159,15 @@ Convert a String "[123, 456, 789]" to an ARRAY[*] OF LINT and returns the number
 > - startIdx out of the array boundaries startIdx : 1 and Array[5..10]
 > - endIdx out of the array boundaries endIdx : 15 and Array[0..10]
 
+## TRUNC
+
+TRUNC() round a floating number no the next DINT value downwards to zero
+
+```iecst
+TRUNC(value : LREAL) : DINT;
+TRUNC(value : REAL) : DINT;
+```
+
 ### Times
 
 Convert the date and time of a SIMOTION system into the data type LDATE_AND_TIME (LDT) and back. The SIMOTION format is a structured data type consisting of two 32-bit values. For the sake of simplicity, they are interpeted as DWORD.
diff --git a/src/TRUNC.st b/src/TRUNC.st
new file mode 100644
index 0000000..699ca62
--- /dev/null
+++ b/src/TRUNC.st
@@ -0,0 +1,34 @@
+NAMESPACE Simatic.Ax.Conversion
+
+    FUNCTION TRUNC : DINT
+        VAR_INPUT
+            Value : LREAL;
+        END_VAR
+        TRUNC := TO_DINT(Value);
+        IF Value > 0.0 THEN
+            IF TO_LREAL(TRUNC) > Value THEN
+                TRUNC := TRUNC - 1;
+            END_IF;
+        ELSE
+            IF TO_LREAL(TRUNC) < Value THEN
+                TRUNC := TRUNC + 1;
+            END_IF;
+        END_IF;
+    END_FUNCTION
+
+    FUNCTION TRUNC : DINT
+        VAR_INPUT
+            Value : REAL;
+        END_VAR
+        TRUNC := TO_DINT(Value);
+        IF Value > 0.0 THEN
+            IF TO_LREAL(TRUNC) > Value THEN
+                TRUNC := TRUNC - 1;
+            END_IF;
+        ELSE
+            IF TO_LREAL(TRUNC) < Value THEN
+                TRUNC := TRUNC + 1;
+            END_IF;
+        END_IF;
+    END_FUNCTION
+END_NAMESPACE
diff --git a/test/TruncateTest.st b/test/TruncateTest.st
new file mode 100644
index 0000000..d443dff
--- /dev/null
+++ b/test/TruncateTest.st
@@ -0,0 +1,134 @@
+USING AxUnit.Assert;
+
+NAMESPACE Simatic.Ax.Conversion
+
+    {TestFixture}
+    CLASS TestTruncate
+
+        {Test (v := 0.0000000000001, e := 0)}
+        {Test (v := 0.4, e := 0)}
+        {Test (v := 0.4000011111231, e := 0)}
+        {Test (v := 0.50000000000001, e := 0)}
+        {Test (v := 0.9, e := 0)}
+        {Test (v := 1.0, e := 1)}
+        {Test (v := 1.4, e := 1)}
+        {Test (v := 1.5, e := 1)}
+        {Test (v := 1.9, e := 1)}
+        {Test (v := 4.98235469312341234, e := 4)}
+        {Test (v := 5.0219410234234, e := 5)}
+        {Test (v := 9.0, e := 9)}
+        {Test (v := 9.4, e := 9)}
+        {Test (v := 9.5, e := 9)}
+        {Test (v := 9.9, e := 9)}
+        {Test (v := 10.0, e := 10)}
+        {Test (v := 10.4, e := 10)}
+        {Test (v := 10.5, e := 10)}
+        {Test (v := 10.9, e := 10)}
+        {Test (v := 100.0, e := 100)}
+        {Test (v := 100.4, e := 100)}
+        {Test (v := 100.5, e := 100)}
+        {Test (v := 100.9, e := 100)}
+        {Test (v := 1000.0, e := 1000)}
+        {Test (v := 1000.4, e := 1000)}
+        {Test (v := 1000.5, e := 1000)}
+        {Test (v := 1000.9, e := 1000)}
+        {Test (v := -0.0000000000001, e := 0)}
+        {Test (v := -0.4, e := -0)}
+        {Test (v := -0.4000011111231, e := -0)}
+        {Test (v := -0.50000000000001, e := -0)}
+        {Test (v := -0.9, e := -0)}
+        {Test (v := -1.0, e := -1)}
+        {Test (v := -1.4, e := -1)}
+        {Test (v := -1.5, e := -1)}
+        {Test (v := -1.9, e := -1)}
+        {Test (v := -4.98235469312341234, e := -4)}
+        {Test (v := -5.0219410234234, e := -5)}
+        {Test (v := -9.0, e := -9)}
+        {Test (v := -9.4, e := -9)}
+        {Test (v := -9.5, e := -9)}
+        {Test (v := -9.9, e := -9)}
+        {Test (v := -10.0, e := -10)}
+        {Test (v := -10.4, e := -10)}
+        {Test (v := -10.5, e := -10)}
+        {Test (v := -10.9, e := -10)}
+        {Test (v := -100.0, e := -100)}
+        {Test (v := -100.4, e := -100)}
+        {Test (v := -100.5, e := -100)}
+        {Test (v := -100.9, e := -100)}
+        {Test (v := -1000.0, e := -1000)}
+        {Test (v := -1000.4, e := -1000)}
+        {Test (v := -1000.5, e := -1000)}
+        {Test (v := -1000.9, e := -1000)}
+        METHOD PUBLIC Test_Different_LREALS
+            VAR_INPUT
+                v : LREAL;
+                e : DINT;
+            END_VAR
+            Equal(expected := e, actual := TRUNC(v));
+        END_METHOD
+
+        {Test (v := REAL#0.0000000000001, e := 0)}
+        {Test (v := REAL#0.4, e := 0)}
+        {Test (v := REAL#0.4000011111231, e := 0)}
+        {Test (v := REAL#0.50000000000001, e := 0)}
+        {Test (v := REAL#0.9, e := 0)}
+        {Test (v := REAL#1.0, e := 1)}
+        {Test (v := REAL#1.4, e := 1)}
+        {Test (v := REAL#1.5, e := 1)}
+        {Test (v := REAL#1.9, e := 1)}
+        {Test (v := REAL#4.98235469312341234, e := 4)}
+        {Test (v := REAL#5.0219410234234, e := 5)}
+        {Test (v := REAL#9.0, e := 9)}
+        {Test (v := REAL#9.4, e := 9)}
+        {Test (v := REAL#9.5, e := 9)}
+        {Test (v := REAL#9.9, e := 9)}
+        {Test (v := REAL#10.0, e := 10)}
+        {Test (v := REAL#10.4, e := 10)}
+        {Test (v := REAL#10.5, e := 10)}
+        {Test (v := REAL#10.9, e := 10)}
+        {Test (v := REAL#100.0, e := 100)}
+        {Test (v := REAL#100.4, e := 100)}
+        {Test (v := REAL#100.5, e := 100)}
+        {Test (v := REAL#100.9, e := 100)}
+        {Test (v := REAL#1000.0, e := 1000)}
+        {Test (v := REAL#1000.4, e := 1000)}
+        {Test (v := REAL#1000.5, e := 1000)}
+        {Test (v := REAL#1000.9, e := 1000)}
+        {Test (v := REAL#-0.0000000000001, e := 0)}
+        {Test (v := REAL#-0.4, e := -0)}
+        {Test (v := REAL#-0.4000011111231, e := -0)}
+        {Test (v := REAL#-0.50000000000001, e := -0)}
+        {Test (v := REAL#-0.9, e := -0)}
+        {Test (v := REAL#-1.0, e := -1)}
+        {Test (v := REAL#-1.4, e := -1)}
+        {Test (v := REAL#-1.5, e := -1)}
+        {Test (v := REAL#-1.9, e := -1)}
+        {Test (v := REAL#-4.98235469312341234, e := -4)}
+        {Test (v := REAL#-5.0219410234234, e := -5)}
+        {Test (v := REAL#-9.0, e := -9)}
+        {Test (v := REAL#-9.4, e := -9)}
+        {Test (v := REAL#-9.5, e := -9)}
+        {Test (v := REAL#-9.9, e := -9)}
+        {Test (v := REAL#-10.0, e := -10)}
+        {Test (v := REAL#-10.4, e := -10)}
+        {Test (v := REAL#-10.5, e := -10)}
+        {Test (v := REAL#-10.9, e := -10)}
+        {Test (v := REAL#-100.0, e := -100)}
+        {Test (v := REAL#-100.4, e := -100)}
+        {Test (v := REAL#-100.5, e := -100)}
+        {Test (v := REAL#-100.9, e := -100)}
+        {Test (v := REAL#-1000.0, e := -1000)}
+        {Test (v := REAL#-1000.4, e := -1000)}
+        {Test (v := REAL#-1000.5, e := -1000)}
+        {Test (v := REAL#-1000.9, e := -1000)}
+        METHOD PUBLIC Test_Different_REALS
+            VAR_INPUT
+                v : REAL;
+                e : DINT;
+            END_VAR
+            Equal(expected := e, actual := TRUNC(v));
+        END_METHOD
+
+    END_CLASS
+
+END_NAMESPACE