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October 6, 2025
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KepServerX - Device is not responding. Connection closed by device

  • October 6, 2025
  • 1 reply
  • 383 views

We are working with PLC Siemens S7-1500 Firmware v4.0. OPC is able to establish connection but at some point it disconnects and gives following error: "Device is not responding. Connection closed by device". Slot and rack in configurtion is correct.

 

PLC Siemens S7-1500 Firmware v4.0

KEPServerEX version 6.18

 

Could you please suggest any solution?

Best answer by rajskumar

Hello,
Assuming you're using the Siemens S7 Plus Ethernet Driver — in version 6.18, we added support for S7-1500 devices with firmware version 4.0, so you should be covered in that regard.

I reviewed the manual, and based on the information provided:

  • Possible Cause: The device refused the connection due to too many connections.
  • Suggested Solution: Verify the number of connections allowed by the PLC.

Kindly check this configuration and see if it resolves the issue. If the problem persists, capturing a Wireshark trace may help us understand what’s happening at the packet level.

Please let me know how it goes. Thanks 

 

rajskumar_0-1759765000096.png

 

 

1 reply

R
rajskumar16-PearlAnswer
16-Pearl
October 6, 2025

Hello,
Assuming you're using the Siemens S7 Plus Ethernet Driver — in version 6.18, we added support for S7-1500 devices with firmware version 4.0, so you should be covered in that regard.

I reviewed the manual, and based on the information provided:

  • Possible Cause: The device refused the connection due to too many connections.
  • Suggested Solution: Verify the number of connections allowed by the PLC.

Kindly check this configuration and see if it resolves the issue. If the problem persists, capturing a Wireshark trace may help us understand what’s happening at the packet level.

Please let me know how it goes. Thanks 

 

rajskumar_0-1759765000096.png

 

 

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