Should I use Art-Net or sACN?
You’ve probably seen both Art-Net and sACN around and maybe you’ve even used them, but have you ever wondered what the difference is? As it turns out, they both offer different ways of achieving the same aim: to get DMX data from your lighting console or software to your pixel controller.
All Advatek PixLite controllers support both Ethernet protocols for the unique benefits each one brings. This article will help you understand each one and determine which you should select for your application.
For personalized advice on which option is best for your lighting project, contact us today.
Broadcast, Unicast And Multicast
Before diving into the benefits of these protocols, we first need to understand the ways in which they transmit their data. There are three ways that this network data can be delivered: broadcast, unicast and multicast. In the diagram below, pixel controllers A and B require the same universes from the sending software, whereas Pixel controller C does not.
In the first configuration, the sending software will transmit the DMX universe to the network, which will deliver it to all three pixel controllers. This one-to-all method is called broadcast. It ensures no device gets excluded from any data, but it will likely cause devices to receive unnecessary traffic – especially when working with a high universe count.
The second configuration uses the unique IP addresses of each pixel controller to deliver specific data to each. The sending software will transmit the universe to pixel controller A, on its IP address, and then do the same for B, on its IP address. This one-to-one method is called unicast. It relies on the knowledge of each device’s IP address, to ensure that devices only receive what the sending software intends. While this method avoids pixel controller C from receiving unnecessary data, it also means that the universe has been transmitted twice, increasing overall network traffic.
The final configuration reduces both network traffic and unnecessary incoming data. The sending software transmits the universe once, and the pixel controllers will subscribe to any universes they need. Pixel controllers A and B will signal the network to subscribe to the universe, and so the data is sent to these two devices but not to device C. This one-to-many method is called multicast and relies on IGMP snooping. For more information, see the article: IGMP Snooping Guide.
Art-Net is designed for broadcast and unicast. sACN is designed for unicast and multicast.
Reducing Network Traffic
Network traffic is increased when universes are transmitted more than they need to be. In broadcast and multicast, each universe is transmitted only once. In unicast, each universe is transmitted as many times as there are pixel controllers who need it. If two controllers need the same universe, then it is sent twice, one per IP address. It is worth noting that in many pixel applications, each PixLite controller requires unique addressing anyway. So, the advantage of transmitting a universe once and multicast delivering it multiple times may not be applicable.
Art-Net may switch a universe to broadcast if it detects too many duplicates being sent – this has its downsides, which will be explored next. If network traffic is a large consideration for you, multicasting via sACN might be best for your application.
Reducing Irrelevant Incoming Data
When Art-Net was first developed, it was used for transmitting a small amount of data. Because of this, broadcasting was not an issue. In modern light displays, however, hundreds of universes may be needed. If all this data is broadcasted, the devices might not be able to handle the sheer volume of data and could result in dropped packets. To avoid this, we need to stay away from broadcasting. Unicasting will achieve this; however, Art-Net can still result in broadcasting if it detects too many duplicate universes being sent.
sACN, on the other hand, was built specifically for large pixel systems. This is why it prohibits broadcasting data. The only time where broadcasting sACN can effectively occur is in the event of a poorly designed network, which we’ll explore next.
If you want to ensure your network devices are not flooded with irrelevant incoming data, then a multicasting sACN approach might be what you need.
Whilst a lighting display doesn’t require a networking degree, there are some aspects to your setup that might benefit from some basic networking knowledge. If you’re just starting out, then an Art-Net approach might be a good method for you, as it will be compatible with most networking equipment and probably won’t require much more configuration than managing IP addresses.
sACN, although offering many benefits, typically requires knowledge of some network design concepts. In order to properly multicast, you’ll need the correct equipment and appropriate device configuration. If IGMP snooping is not supported or properly configured, it might result in the multicast data effectively being broadcast, or not even delivered at all.
Reducing Setup Time
Since the release of Art-Net 4, setup time has been dramatically reduced, allowing for proper automatic discovery of pixel controllers on a network. While previous versions allowed some form of discovery, the fourth generation now provides sending software the ability to discover devices with many universes correctly (such as PixLite controllers). Unicasting with Art-Net is therefore made quick to setup, as all the IP addresses can be discovered for you.
sACN was built for multicasting, which provides the ability for pixel controllers to subscribe to the universes they need. This means that when setting up the sending software, you won’t need to worry about which IP address belongs to each controller. Previous versions of Art-Net could not compete with the fast setup time of sACN, however with Art-Net 4, both protocols now boast impressive setup times.
When a light display is running, it’s imperative that connections remain stable. A connection that is often overlooked is the IP address of the pixel controller. If this address is changed, it needs to remain operational. Unicasting through Art-Net requires stability of the addresses of all devices. If an Art-Net device loses its IP address, it will need to be rediscovered in sending software for it to become operational again. For this reason, Art-Net installations will typically be set up to use static IP addresses.
Multicasting through sACN works regardless of the IP address of the pixel controllers. If something happens to a controller’s IP address (e.g. it is changed by a DHCP server), it will seamlessly continue receiving the multicast traffic without human intervention. Whether your network will benefit from this behavior will depend on your application.
Get In Touch With The Team At Advatek Lighting
Another factor to consider before choosing between Art-Net and sACN is whether your lighting software and pixel controllers can support these protocols. Fortunately, all PixLite pixel controllers provide support for both protocols, so the choice might depend only on what your lighting software supports. If your lighting software supports both and you’re still not sure which one to choose, get in touch with the team at Advatek Lighting to find out how Advatek can help you.