Issue
- Xenta Controllers can report "offline" status if they encounter bandwidth limitations
- Completion Event Failure warnings
- CRC Errors showing in controller properties
- Loytec Multi-port router/switch channel LED blinking fast red (traffic overload)
Product Line
TAC Vista
Environment
- Lon Networks
- Vista
- Xenta
- LPA Loytec Protocol Analyzer
Cause
HMI Vista on-line/off-line presentation is based upon receipt of the heartbeat messages. Every TAC Xenta 280/300/401 controller is periodically sending a message to the other members of its TAC Xenta reporting (including the group master) that it is on-line.
Proprietary "LACNet-IAm" and "LACNet-GroupIs" are sent every 15 seconds to HMI Vista. Without the HMI receiving these heartbeats, Vista will display the controller or group in an offline state. The TAC Xenta group is specified by the tag_0 and the TAC Group is specified by tag_1 bindings in LonMaker or NL220.
Resolution
Actions for reducing Bandwidth:
TAC Xenta 100s
- Slow down the SendHeartBeat
- Check sensors etc that are affecting all bound nvo's
- Decrease traffic of SNVT group bindings. For large groups of bound controllers, use UNACKD/RPT instead of ACK service type.
3rd Party LonWorks devices
- Change update rates for nvo's. If possible, the product manual should show how.
- Decrease traffic of SNVT group bindings. For large groups of bound controllers, use UNACKD/RPT instead of ACK service type.
TAC Xenta 280/300/401 TACNV and SNVTs
- Verify delta and period values make sense for the particular signal and application.
- Decrease traffic of SNVT group bindings. For large groups of bound controllers, use UNACKD/RPT instead of ACK service type.
- Increase the trend log time span (the total log time) if possible. Of course, this will increase the memory usage in the Xenta, but this will make TAC Vista to do the fetch more seldom and result in reduced traffic.
TAC Xenta 280/300/401 + TAC Xenta I/O Modules
- If sensitive sensors (i.e. pressure sensors) are connected to I/O Modules, a high load of communication will be generated. Bandwidth issues may arise when 401s with many I/O Modules are each reading multiple sensitive sensors.
- Increase the Min Send Time for every I/O Module. Min Send Time is how often the I/O module is allowed to communicate with the TAC Xenta. This setting is located in Device Specification in Menta.
- Reduce Trend Log definitions in the controllers.
- If possible, try to have all your "high speed sensors" connected to one, or a few I/O modules, so it's only a few I/O modules sending a lot to the Xenta.
LonWorks routers
- Implement L-Switch routers to reduce traffic on high bandwidth segments.
- Set router to Configured Mode, not Repeater Mode.
Vista Server Trend Log
- Stagger Vista server Trend Log start times so that they do not all attempt to get fetched at once.
See also Troubleshooting LON Network Communication
More information can be found in Tool for LON / LPA Capture Traffic Analysis (login required) which discusses the LPA Analyzer Tool. This may be useful for interpreting the LP file data.
