Sigma – Communication Failure with DNNs and ARCnet Sub-LANs Due to Windows Firewall

[Product_Support]

Issue

Sigma controllers, including DNNs and ARCnet sub-LANs, are not communicating with the Sigma server. Communication appears to be completely blocked or intermittent.

Product Line

Satchwell BAS & Sigma

Environment

Satchwell Sigma

Cause

Communications with the Sigma controllers are not possible because the Windows Firewall is blocking messages.

The Windows Firewall on the Sigma server is blocking UDP traffic required for communication with Sigma controllers and DNNs. Specifically, the firewall is preventing:

• UDP port 49152, used by Sigma
• UDP port 520, used by the RIP Listener service

This results in the Sigma server being unable to communicate with devices on ARCnet or Ethernet subnets via DNNs.

Resolution

Step 1: Verify Communication

• Temporarily disable the Windows Firewall on the Sigma server.
• Check if communication with Sigma controllers and DNNs is restored.
  • If communication resumes, the firewall is the likely cause.

Step 2: Configure Windows Firewall Exceptions

1. Open Windows Firewall Settings.
2. Navigate to the Exceptions tab (or Allow an app or feature through Windows Firewall in newer versions).
3. Click Add Port:
   • Name: Sigma
   • Port Number: 49152
   • Protocol: UDP
   • Click OK
4. Click Add Port again:
   • Name: RIP
   • Port Number: 520
   • Protocol: UDP
   • Click **OK`
5. Ensure both exceptions are enabled.
6. Re-enable the Windows Firewall and test Sigma communications.

Step 3: Alternative – Persistent Routing

• If your system uses persistent routes instead of RIP Listener, refer to the article:
  Persistent Routing on the Sigma Server