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Guides: Fail-Over

This note describes how Artistic Licence products can handle a sudden loss of data.

The term ‘fail-over’ has a subtly different meaning depending on the circumstances. The key difference is whether one looks at the situation from the perspective of the controller or the receiver. But in either case, the important consideration is that the lights go to a known condition when DMX512 data loss occurs.


The majority of Artistic Licence receivers, such as sunDial, candlePower and Rail-Switch have the ability to detect loss of DMX and take action. The action can be to ‘hold last state’ which is the default for DMX512 equipment, or playback a preset scene. These features are all programmed via RDM (Remote Device Management).


Dealing with a controller failure requires a combination of products to detect the fault and then take action. There are two key approaches: merge and switch.


DMX mergers such a Rail-Merge and matisse f6 have the ability to hold last state. This means that if the DMX512 control signal is lost, they will keep outputting the last signal they received. This approach is useful in some circumstances but lacks flexibility.


Fail-over is further complicated when multiple universes need to be protected. Rail-Flip can protect four universes of DMX512. In automatic mode, it monitors the inputs and if it detects a loss of signal on any of the A-inputs, it will switch to the B-input. Additionally, the product uses relays to do the switching, so it also protects against power loss.

In this approach, fail-over switches to a second DMX controller, such as a matisse f6.


Gateways convert ethernet Art-Net or sACN to DMX512/RDM. So what happens if the ethernet control signal is lost? The premium range gateways such as dataLynx, netLynx and artLynx quad have fail-over detection. This means that you can program what the gateway should do in the event of network failure. The action can be to ‘hold last state’ which is the default, or playback a preset scene. These features are all programmed via DMX-Workshop or the gateway’s web browser.

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Interface: Setting Rail-Switch to trigger on loss of DMX512

There are numerous instances when it is usual to switch a circuit in the event of a DMX512 failure. Rail-Switch II provides this function using its Data Loss Mode (highlighted below). This application note shows how to use DMX-Workshop to configure the product.

Right click and select ‘Set Data Loss Mode’ from the popup menu.

Select scene 1 and press set.

Next, output levels to set the relays to the state to be used in a data failure. In this example it is just the first two relays on.

Right click on ‘Capture preset’ and select ‘Set Capture preset’ from the popup menu.

Select ‘Record scene 1’ and press record.

The Rail-Switch will now output scene 1 in the event of a loss of DMX512.

The standard product (firmware V8.23 or V8.27) will detect loss of DMX512 after approximately 1.8s. A fast response version (V8.25) is available which switches in under 0.5s.