Nodes with more than 4 ports

Nodes with more than four ports

The Art-Net protocol sets a limit of 4 DMX input or output ports. This is because the ArtPollReply packet has a fixed array size.

To overcome this limitation, the concept of a BindingIp was introduced. Any Art-Net node that wishes to support more than 4 DMX ports sends multiple ArtPollReplies on receipt of an ArtPoll. However each ArtPollReply must be sent from a different IP address.

In the ArtPollReply, the BindIp field is set to the IP address of the root IP address of the node. A field called BindIndex is used to order the data.

For example, consider a node with 12 DMX output ports. Let’s say its root IP address is The following table shows how the 3 ArtPollReplies will be structured:


An Art-Net controller will parse these packets to discover which ports are at which IP address. It will then unicast to those discovered IP addresses. The following is the discovery table:

table2Equally, for a node with 4 or less ports, the following table shows the structure:


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