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Asked:20 Oct 2025

Communication / Networks: S1200 Networking issues

Hello,
I am an intern just learning about PLC's. I was given a siemens PLC, 1211C DC/DC/DC. Originally, I was following the manual and was able to find the PLC, Flash the LED's, and connect to it using Portal V11 SP1. I was then given a program to try to run. I had to upgrade to Portal V11 SP2. Upon doing so, I can no longer find the PLC or flash the LED's.
I've been trying to trouble shoot. I was able to ping the IP (4 sent 4 recieved 1 ms max delay) and even was able to compile and download a blank program, however when I try to find it, I get "No accessible device found in selected network" even though I was able to find it before, plus am able to ping it and download to it.
I tried doing online diagnostics, and it found somethign with that IP address, but when I try to Flash LED's, it doesn't work.
I hope I was specific enough about the problem and am curious as to what I should attempt next.

#sosflex #Communication / Networks #siemens
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Answers(1)
Siemens Test Added an Answer on20 Oct 2025

Siemens Self Support - PLC Connection Issue (S7-1211C)

Hello! It sounds like you're encountering a common issue after upgrading your TIA Portal version. Here's a breakdown of potential causes and troubleshooting steps:

Possible Causes:

  • Network Configuration Mismatch: The upgrade to V11 SP2 might have altered network settings or introduced a conflict.
  • PLC Firmware Compatibility: While you can download, the firmware might not be fully compatible with the diagnostic features in SP2.
  • Access Permissions/Security Settings: SP2 might have stricter security protocols affecting device discovery.

Troubleshooting Steps:

  1. Verify Network Settings: Double-check the PLC's IP address, subnet mask, and gateway in TIA Portal *exactly* match the PLC's physical configuration and your network.
  2. Check PLC's PROFINET Interface: Ensure the PROFINET interface on the PLC is active and configured correctly.
  3. TIA Portal Device Discovery Filters: In TIA Portal, when searching for the PLC, ensure no filters are applied that might exclude it.
  4. Restart PLC & TIA Portal: A simple restart of both can often resolve temporary communication glitches.
  5. Firmware Update: Consider updating the PLC's firmware to the latest version compatible with TIA Portal V11 SP2. See Siemens Support Article for firmware updates.
  6. Check Firewall: Ensure your computer's firewall isn't blocking communication with the PLC on the necessary ports.

Since you can ping and download, the basic connection is there. The issue likely lies in the diagnostic communication or discovery process. If these steps don't resolve the problem, please open a Siemens Support Request with your specific TIA Portal and PLC firmware versions for further assistance.

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