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Check active DNC connections

Press MOD key, select 'Communication' menu, then 'Ethernet' to view current active client connections and their status.

Look for duplicate or orphaned connections from the same IP address

Verify MP7210 parameter setting

Access machine parameters via MOD key, navigate to MP7210 (Max. number of Ethernet clients) and check if the value is appropriate for your network setup.

Changing this parameter requires control restart and may affect network performance

Disconnect unnecessary clients

Close unused DNC software, CAM applications, or remote monitoring tools that may be maintaining open connections to the TNC control.

Use 'netstat' command on connected PCs to identify active connections to the control's IP address

Reset Ethernet communication

In MOD menu under 'Communication' > 'Ethernet', select 'Reset Ethernet' to clear all active connections and allow fresh connections.

This will disconnect all current network communications temporarily

Identify monitoring applications

Check factory network for active monitoring software, SCADA systems, or multiple operator panels connected to the same TNC control.

Common culprits include Nagios, PRTG, or custom monitoring scripts with short polling intervals

Review MP7211 timeout setting

Access MP7211 (Ethernet client timeout) via MOD > Machine Parameters and verify the timeout value allows proper connection cleanup.

Setting timeout too low may cause legitimate connections to drop prematurely

Configure connection pooling

Modify monitoring software to use connection pooling or reduce polling frequency to minimize concurrent connections to the TNC.

Implement a single gateway application that polls the TNC and serves data to multiple monitoring clients

Adjust MP7210 if necessary

If legitimate monitoring is required, carefully increase MP7210 value while monitoring system performance and memory usage.

Higher client limits consume more system memory and may impact real-time performance

Check connection status table

In MOD > Communication > Ethernet menu, review the client connection table for connections showing unusual status or very long connection times.

Look for connections with status 'ESTABLISHED' but no recent activity timestamps

Verify MP7211 timeout function

Ensure MP7211 (Client timeout in seconds) is set to a reasonable value (typically 300-600 seconds) to automatically clean up inactive connections.

Verify timeout setting won't interfere with legitimate long-running operations

Perform controlled restart

Execute a controlled restart of the TNC control to clear all network connection states and reset the Ethernet communication subsystem.

Ensure no machining operations are active and coordinate with production schedule

Update network drivers

Check TNC software version and consider updating if known Ethernet communication issues exist in current version.

Consult HEIDENHAIN service bulletins for Ethernet-related fixes in newer software versions

Document current network requirements

List all legitimate network clients including DNC software, monitoring systems, backup applications, and remote access tools that need TNC connectivity.

Include future expansion needs when calculating required client connections

Review MP7210 current setting

Access MOD > Machine Parameters and check MP7210 value against documented network requirements, typical range is 5-20 clients.

Consult machine builder documentation before changing this parameter

Verify related Ethernet parameters

Check MP7200 (Ethernet enable), MP7201 (IP address), MP7211 (timeout), and other 72xx series parameters for proper configuration.

Document all current settings before making changes for easy rollback if needed

Test configuration changes

After parameter changes, restart control and systematically test each network client connection to verify proper operation without alarm recurrence.

Monitor system performance closely after increasing client limits to ensure no degradation