diff --git a/S7.Net/PLC.cs b/S7.Net/PLC.cs
index d997b7a..8d98d4f 100644
--- a/S7.Net/PLC.cs
+++ b/S7.Net/PLC.cs
@@ -218,6 +218,27 @@ namespace S7.Net
                 .Sum(len => (len & 1) == 1 ? len + 1 : len);
         }
 
+        private static void AssertReadResponse(byte[] s7Data, int dataLength)
+        {
+            var expectedLength = dataLength + 18;
+
+            PlcException NotEnoughBytes() =>
+                new PlcException(ErrorCode.WrongNumberReceivedBytes,
+                    $"Received {s7Data.Length} bytes: '{BitConverter.ToString(s7Data)}', expected {expectedLength} bytes.")
+            ;
+
+            if (s7Data == null)
+                throw new PlcException(ErrorCode.WrongNumberReceivedBytes, "No s7Data received.");
+
+            if (s7Data.Length < 15) throw NotEnoughBytes();
+
+            if (s7Data[14] != 0xff)
+                throw new PlcException(ErrorCode.ReadData,
+                    $"Invalid response from PLC: '{BitConverter.ToString(s7Data)}'.");
+
+            if (s7Data.Length < expectedLength) throw NotEnoughBytes();
+        }
+
         #region IDisposable Support
         private bool disposedValue = false; // To detect redundant calls
 
diff --git a/S7.Net/PlcAsynchronous.cs b/S7.Net/PlcAsynchronous.cs
index 2a2de3e..9e82c8d 100644
--- a/S7.Net/PlcAsynchronous.cs
+++ b/S7.Net/PlcAsynchronous.cs
@@ -388,8 +388,7 @@ namespace S7.Net
             await stream.WriteAsync(package.Array, 0, package.Array.Length);
 
             var s7data = await COTP.TSDU.ReadAsync(stream);
-            if (s7data == null || s7data[14] != 0xff)
-                throw new PlcException(ErrorCode.WrongNumberReceivedBytes);
+            AssertReadResponse(s7data, count);
 
             for (int cnt = 0; cnt < count; cnt++)
                 bytes[cnt] = s7data[cnt + 18];
diff --git a/S7.Net/PlcSynchronous.cs b/S7.Net/PlcSynchronous.cs
index 7d2ef01..c101b3e 100644
--- a/S7.Net/PlcSynchronous.cs
+++ b/S7.Net/PlcSynchronous.cs
@@ -353,8 +353,7 @@ namespace S7.Net
                 stream.Write(package.Array, 0, package.Array.Length);
 
                 var s7data = COTP.TSDU.Read(stream);
-                if (s7data == null || s7data[14] != 0xff)
-                    throw new PlcException(ErrorCode.WrongNumberReceivedBytes);
+                AssertReadResponse(s7data, count);
 
                 for (int cnt = 0; cnt < count; cnt++)
                     bytes[cnt] = s7data[cnt + 18];