diff --git a/src/revpimodio2/helper.py b/src/revpimodio2/helper.py
index f1e9176..81b9115 100644
--- a/src/revpimodio2/helper.py
+++ b/src/revpimodio2/helper.py
@@ -531,20 +531,23 @@ class ProcimgWriter(Thread):
                 continue
 
             try:
-                for dev in self._modio._lst_refresh:
-                    if not dev._shared_procimg:
-                        continue
-                    # Set shared outputs before reading process image
-                    for io in dev._shared_write:
-                        if not io._write_to_procimg():
-                            raise IOError("error on _write_to_procimg")
-                    dev._shared_write.clear()
-
                 fh.seek(0)
                 fh.readinto(bytesbuff)
 
                 for dev in self._modio._lst_refresh:
                     with dev._filelock:
+                        if dev._shared_procimg:
+                            # Set modified outputs one by one
+                            for io in dev._shared_write:
+                                if not io._write_to_procimg():
+                                    raise IOError("error on _write_to_procimg")
+                            dev._shared_write.clear()
+
+                            # Read all device bytes, because it is shared
+                            fh.seek(dev.offset)
+                            bytesbuff[dev._slc_devoff] = \
+                                fh.read(len(dev._ba_devdata))
+
                         if self._modio._monitoring or dev._shared_procimg:
                             # Inputs und Outputs in Puffer
                             dev._ba_devdata[:] = bytesbuff[dev._slc_devoff]
diff --git a/src/revpimodio2/io.py b/src/revpimodio2/io.py
index df72dc5..ceafcb3 100644
--- a/src/revpimodio2/io.py
+++ b/src/revpimodio2/io.py
@@ -594,6 +594,7 @@ class IOBase(object):
                     return False
 
         else:
+            # Write one or more bytes to process image
             value = bytes(self._parentdevice._ba_devdata[self._slc_address])
             with self._parentdevice._modio._myfh_lck:
                 try: