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Link Noise

Link Noise is any sort of electrical signals that are received by the Processor from the Mux/Muxbar cables of a QS link that do not have any information relevant to the system. Depending on how the system is built, some Link Noise is to be expected, however it should stay steady and not increase over time.

Article Contents:

1. Symptoms of Link Noise
2. How Does Link Noise Work?
3. How to Determine the Source of the Link Noise
4. Best Practices

Symptoms of Link Noise

Link Noise does not always cause issues immediately. Most of the time it grows slowly, creating issues in the system later on, particularly when returning to the site for future transfers or activation.

There are a variety of symptoms that could indicate a Link Noise issue:

• Scrolling (Waterfalling) keypads
• Unresponsive devices on the QS link
• Shade Power Panel blink codes (Usually regarding the Diagnostic LED)
• Inability to connect via the app
• Inability to transfer to the system
  • Having various devices fail during the transfer that should be responding, or are responding via the Diagnostic Tab
• Link Health indicators on the processor are blinking yellow or red
• Shades randomly throwing a solid red light blink code

How Does Link Noise Work?

Link Noise occurs for a variety of reasons. We've listed some of the common causes below:

• Somewhere in the QS link the 3 and 4 wire (Mux and Muxbar) got swapped.
  • This commonly happens on Wire Landing Boards.
• A device is in an error state (such as a blinking output on a shade panel or a Zone on a din-rail module)
• There's a short happening between the 1 or 2 wires with either the 3 or 4 wires
  • This is commonly caused by a stray strand making contact on a phoenix connector.

When it comes to determining if the issue is being caused by Link Noise, aside from the symptoms above, you can use the Terminal feature of Lutron Designer to see what the Link Noise count is on that particular link. This number is cumulative, meaning the number will never reduce unless the processor is power cycled, or a transfer/firmware upgrade/factory default occurs. Follow the steps below to see your noise level:

1. Open Terminal by going to Tools > Terminal
2. Select your processor's IP address at the top drop-down menu and select Connect
3. At the bottom of the window, select the Command drop down and select Processor > Processor Link Health
   1. You may need to press the + icon to expand Processor to access the Processor Link Health Option
4. Select the Link you suspect may have Link Noise
5. Press Send.

You'll receive a response back with a variety of Link Health values seen below:

8/5/2024 2:03:23 PM: Request Sent:- {"CommuniqueType":"CreateRequest","Header":{"Url":"/reportgenerator"},"Body":{"LinkHealthReportParameters":{"ReportType":"LinkHealthReport","Links":[{"href":"/link/791"}]}}}
8/5/2024 2:03:23 PM: Response Received :-{"CommuniqueType":"CreateResponse","Header":{"MessageBodyType":"MultipleLinkHealthValuesResult","StatusCode":"201 Created","Url":"/reportgenerator"},"Body":{"LinkHealthReportParameters":{"ReportType":"LinkHealthReport","Links":[{"href":"/link/791"}]},"LinkHealthValues":[{"Link":{"href":"/link/791","LinkType":"QS"},"QSLinkHealth":{"NoiseError":0,"OverrunError":0,"FramingError":0}}]}}

• The last line is the most important, as it will show you your NoiseError count, along with the other errors that are usually present with Noise.

You can also use the Lutron Connect Portal to view the Link Noise present on the link within the System Monitor. 

• For more details on this, please see our Lutron Connect Portal Article.

How to Determine the Source of the Link Noise

Link noise can be tedious to track down, as the system cannot pinpoint the source of the noise, but there are some steps that can be done to make it easier to track down.

A few things to note beforehand:

• Link noise is cumulative. This means it will usually never lower unless the processor or link restart.
• Having Link Noise that does not change is fairly normal for all systems
  • If the Link Noise is increasing, this is not normal.
• If Keypads are connected to a link with no other devices on the system to control (such as dimmers or Din-Rail Modules), there should almost always be 0 Link noise.
• Having a link separated into loops using a Wire Landing Board is a best practice that will make this process much easier.

In general, we recommend following these steps to narrow down the source of the noise:

1. Disconnect the link from the processor showing symptoms of Link Noise
2. Power cycle the processor to reset the Link Noise count to 0
3. Use Terminal to verify the Link Noise has remained at 0.
4. Starting with devices such as shades and Din-Rail modules, plug in one group at a time and monitor the Link Noise via the Terminal commands
   1. Minor jumps in link noise is normal when reconnecting these devices, as they are communicating out to the system again.
5. If the Link Noise stays steady after a few minutes from reconnecting, plug in the next group of devices.
6. Once you've located a group that is causing a consistent growth of Link Noise, disconnect that group and power cycle the processor to 0 out the Link Noise counter again.
7. Disconnect all devices except one in the problem group and reconnect the link.
8. Monitor the Link Noise again to see which device causes a growth in the noise counter.
9. Once the device(s) located, verify the wiring or use a test wire to verify if it's the device or wiring causing the noise.
10. If a replacement is needed under warranty, ensure you generate a Support File from the system before contacting us; we'll be able to verify the device via serial number and see the troubleshooting done to approve the replacement.

Best Practices

Below are some of our recommended practices when wiring a QS link to avoid Link Noise, or to make troubleshooting it easier:

• Separate devices into 'loops' that can be disconnected in groups.
• Wire Landing boards are great for keeping track of loops, however, make sure you only have one loop per landing.
• After finishing a project it's always a good idea to check the Link Health via Terminal to see if there's any climbing link noise
  • Remember; Link Noise is not always present immediately. Most of the time it will slowly cause issues over time, or when next on-site transferring/firmware upgrading.
• After installation, before activation, and after activation make sure to check any panelized devices for error codes
  • For shade panels, ensure the output lights are solid and the diagnostic light is on or flashing
  • For din-rail modules, ensure the zone lights are not displaying any blink codes. To verify what the blink codes mean, please see their respective installation guides.