Troubleshooting S7 Ethernet connections

Can you Ping the S7 that is not communicating from the PC with the TOP Server?

• No - Check the IP of the S7 with the programming software and the Ethernet Network
• Yes - Verify the IP address in the TOP Server Device properties matches the IP address.  If it does, go to the next question

Are both S7 devices configured under their own channel in the TOP Server?

• No - See our post Using Multiple Channels in TOP Server to Optimize Performance here, which will explain the values of setting up devices under there own channel when using an Ethernet connection (this does not apply to Wireless or modem connections).  Now go to the next question if you still can't get communications.
• Yes - Go to the next question

Check that you have the right settings under the Device Properties - S7 Comm. Parameters

• Verify that the CPU settings are correct for this PLC
• Check the link Type.  Does this PLC have any available connections for this Link Type?  The programming software can be used to determine what type of links are available for this connection.  The help file for the driver under Device Setup - S7 Comm. Parameters show how may connections we support for each link type for the different PLC models.  We have had customer's connect with more connections then shown it the help file for Siemens PLCs that have expanded the number of connections supported.

If none of the above steps gets you going it is possible the subnet mask and gateway are set differently in the PLC and your PC.  If you are using a switch this might need to be configured to address these settings also.  You should also verify that the PLC can communicate with the programming software through the Ethernet module.