Troubleshooting

Behavior	Category	Description
No connection is established. The connector goes into the 0xF3 TCP Timeout state.	Connector	No TCP connection to the S7 Controller can be established. Please check whether the controller can be reached from your target system, e.g. via a ping command.
No connection is established. The connector goes into the 0xF3 TCP Timeout state. The IP address of the S7 Controller can be reached via a ping command.	Connector	Please check whether the required S7 Controller is behind the IP address.
No connection is established. The connector goes into the 0xF4 COTP Setup Error state.	Connector	A TCP connection with the S7 Controller could be established, however the connection to the S7 Communication Service failed. Please check whether the connection parameters "CPU Type", "Rack" and "Slot" match the required S7 Controller.
The TCP connection to the S7 Controller cannot be established.	Connector	Please ensure that there are no firewalls between the TwinCAT device and the S7 Controller that could block the data connection or that the corresponding communication port is allowed in the firewall. Siemens S7 Controllers use TCP port 102 for incoming connections.
No connection is established. The connector goes into the 0xF2 TCP Setup Error state. The logger displays the following message: S7Connection: src ip address is invalid – maybe ethernet device is not supported?	Connector	Please make sure that the selected network adapter at the Realtime Ethernet Device has received a valid IP address. If the IP address on the adapter is 0.0.0.0, please check that your DHCP server is functioning correctly or manually assign an IP address for the adapter – either in the Windows network settings or in the "Parameters (Init)" dialog from the TCP/UDP RT device.
After a Write command, the following messages appear in the logger: S7Connection: S7 error, errorClass 0x81, ErrorCode 0x04 S7Connection: Please check if remote access is enabled on Siemens Controller S7Connection State = 0xF5	Request	Generally, this error means that a certain function is not supported by the S7 device. This error usually only occurs with S7-1200 and S7-1500 Controllers if remote access has not been activated. However, some S7 Controllers (e.g. S7-412-1) only allow 2-byte data types for a write operation, e.g. WORD, which means that this error code can also occur during a write operation.
After a read/write command, the connection is in the 0xF5 S7 Error state. The entry "CS7Connector::ReceiveS7Comm()<<< S7 error, errorClass 81, Error code 04" is found in the logger	Request	The remote access on the S7 Controller is not enabled. See also chapter Activating the S7 protocol access.
After a read/write command, the request is in an error state. The second nibble of the error variables is at the value 3 (Address out of range).	Request	Option 1: The configuration parameter "S7 Byte Address" is greater than the data area of the requested "Data Area". Option 2: Please check the setting "Optimized Block Access" on the requested data block of the S7 Controller. You can find further information about this in the chapter Activating the S7 protocol access.
After a read/write command, the request is in an error state. The second nibble of the error variables is at the value 6 (Object does not exist).	Request	The requested object is not on the S7 Controller. Please check whether the configuration parameter "S7 Data Block" was set correctly.
After a read command, incorrect values are displayed.	Request	Please check whether the address data of the S7 data point were selected correctly or whether they have been changed, e.g. by a change in the S7 control program.
I cannot add an Input Data Area to a write request	Request	Writing input variables is not permitted.
I added the symbol server to the target browser, but I don't see any variables.	Symbol server	Please make sure that you use TwinCAT 3.1 Build 4024.14 at minimum on the system that you have activated the project on. The symbol server interface is only available from this TwinCAT version.