diff --git a/revpimodio2/__init__.py b/revpimodio2/__init__.py
index f1c3100..837ded0 100644
--- a/revpimodio2/__init__.py
+++ b/revpimodio2/__init__.py
@@ -33,6 +33,7 @@ BOTH = 33
 INP = 300
 OUT = 301
 MEM = 302
+PROCESS_IMAGE_SIZE = 4096
 
 
 class DeviceNotFoundError(Exception):
diff --git a/revpimodio2/device.py b/revpimodio2/device.py
index c6475a4..e52c51c 100644
--- a/revpimodio2/device.py
+++ b/revpimodio2/device.py
@@ -298,7 +298,7 @@ class Device(object):
         if len(dict_io) <= 0:
             return slice(0, 0)
 
-        int_min, int_max = 4096, 0
+        int_min, int_max = PROCESS_IMAGE_SIZE, 0
         for key in sorted(dict_io, key=lambda x: int(x)):
 
             # Neuen IO anlegen
@@ -1273,4 +1273,4 @@ class Virtual(Gateway):
 
 # Nachträglicher Import
 from .io import IOBase, IntIO, IntIOCounter, IntIOReplaceable, MemIO
-from revpimodio2 import INP, OUT, MEM
+from revpimodio2 import INP, OUT, MEM, PROCESS_IMAGE_SIZE
diff --git a/revpimodio2/io.py b/revpimodio2/io.py
index ba5ceec..f4021ef 100644
--- a/revpimodio2/io.py
+++ b/revpimodio2/io.py
@@ -4,7 +4,8 @@ import struct
 from re import match as rematch
 from threading import Event
 
-from revpimodio2 import BOTH, FALLING, INP, MEM, OUT, RISING, consttostr
+from revpimodio2 import BOTH, FALLING, INP, MEM, OUT, RISING, consttostr, \
+    PROCESS_IMAGE_SIZE
 
 __author__ = "Sven Sager"
 __copyright__ = "Copyright (C) 2018 Sven Sager"
@@ -37,7 +38,7 @@ class IOList(object):
 
     def __init__(self):
         """Init IOList class."""
-        self.__dict_iobyte = {k: [] for k in range(4096)}
+        self.__dict_iobyte = {k: [] for k in range(PROCESS_IMAGE_SIZE)}
         self.__dict_iorefname = {}
 
     def __contains__(self, key):