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Siemens Device Returning Protocol Error [Class=0x81, Code=0x04]


Last Update: 11/7/2018
Problem:
The Event Log displays the error message, "Unable to read # bytes starting at offset 0 for <requested tag> on device <channel.device>. Device returned protocol error [Class=0x81, Code=0x04]."

Possible Cause:
The controller's Protection settings are directly related to protocol error [Class=0x81, Code=0x04]. If the Protection settings match the "Access Level" and "Permit access with PUT/GET communication from remote partner" options specified in the Siemens TCP/IP Ethernet Driver product manual, then the controller's memory (that is, the SIMATIC memory card) may need to be reset.

Solution:
Reset the controller's memory and then download the S7 project. At that point, the Siemens TCP/IP Ethernet Driver should be able to access the controller's memory.

Note:
For more information, refer to "How To Configure S7-1500 Connections" in the Siemens TCP/IP Ethernet Driver product manual.