Point-to-point connections vs. Network connections
Musicians are used to using a cable to connect one piece of hardware directly to another: for example a cable that connects your guitar to your amp, or a cable that connects your microphone to your audio interface. This is what we call a point-to-point connection - it’s a straight line from point A to point B. That’s fine for very simple connections, but creating more complex signal flows requires a lot of additional hardware, such as more cables, a mixing desk etc. Or in the case of MIDI, a lot of DIN-MIDI cables and MIDI interface connections.
Ethernet can work the same way if you want. You can simply run an Ethernet cable directly from your computer to your iConnectivity MIDI interface and it will work fine, just the same way you might use a USB cable. But that’s only using a fraction of the true power of Ethernet.
One of the great things about using Ethernet is that it doesn’t have to be a point-to-point connection. Ethernet is designed to be able to create multiple virtual connections between any and all devices on a network. So if you have more than one computer or more than more interface or network device, a much better way to connect them is via an Ethernet switch in a “star” configuration. It’s called a star configuration because the Ethernet switch acts as the central hub of your MIDI solar system, with your computers and interfaces positioned around it, as in the diagram below.
Wiring up your system like this enables you to virtually connect any of your MIDI devices to any other device on the network or even multiple devices at once. It also allows you to use multiple computers at the same time and transfer MIDI data between them. For this reason we strongly recommend the use of an Ethernet switch to set up a star network for anything beyond the most basic MIDI systems.
Note that you don’t need to have specialised network hardware for your MIDI gear. You can connect your computers and interfaces to any standard Ethernet switch, or to the Ethernet jacks on the back of your home Internet router. You can even use Powerline connectors to send your Ethernet MIDI signals around your studio using just the existing electrical wiring in the walls!
Once you have your system physically wired up like this, all you have to do is tell the network which signals you want sent to where. RTP-MIDI uses a system of “virtual MIDI cables”. You create these virtual connections using the RTP-MIDI software on your computer and use them to route MIDI signals between your computers and iConnectivity interfaces. So you get all the advantages of having hundreds of possible connections without having to have hundreds of real cables taking up space.
To recap: the physical cabling of an Ethernet network has nothing to do with the signal flow of your MIDI data! As long as you have each computer and interface physically connected to your network switch, then every MIDI device can communicate with every other one - no direct cables needed between them! This will enable you to create a highly sophisticated and powerful MIDI system with a minimum of effort.
How many channels can I have on my MIDI network?
In most cases the answer to this question is very simple: as many as you like!
Like USB-MIDI, RTP-MIDI uses a system of virtual MIDI ports. However where USB-MIDI is limited to a maximum of 16 MIDI ports per cable, the number of virtual ports you can have on an RTP-MIDI network is effectively unlimited.
Ethernet is capable of carrying thousands of MIDI channels down one single cable, so an RTP-MIDI network is infinitely expandable. The only limitation is in the RAM capability of the devices connected to the network. Since most modern computers have huge amounts of RAM, each computer connected to an RTP-MIDI Ethernet system can create and use as many virtual MIDI ports are required. The only real bottleneck lies in the MIDI interfaces connected to the network.
Current iConnectivity interfaces such as the MIDI4+, mio4, mio10, and PlayAUDIO12 can handle up to 4 virtual RTP-MIDI ports each. This means that each individual interface can send and receive 4 ports of 16 channels, or 64 channels per interface. So in a standard star network like the diagram below, the MacBook on the left can send up 64 MIDI channels to each of the 3 interfaces on the right, or 192 MIDI channels in total:
Each of the two computers in the diagram above can also send as many MIDI channels as they want to each other, since they have effectively no limitations on their own internal RTP-MIDI ports. So for example if you wanted to run a DAW on the MacBook and some virtual instruments on the Windows laptop, you could run as many virtual instruments as you need and communicate to each one via its own individual RTP-MIDI port.
Combining Point-to-Point connections with a Star network
It’s important to remember that in most cases the optimal solution is to use a star connection for your main central RTP-MIDI infrastructure, and then combine that with point-to-point connections at the “edges” of your network. You will normally connect your computers and interfaces in a star via your Ethernet switch, and then connect only your other MIDI devices to your interfaces using DIN-MIDI or USB-MIDI connections.
In some specialised cases however you may want to do things slightly differently - for example when using an iConnectivity PlayAUDIO12 interface for audio and MIDI playback redundancy in a live show scenario. In this case you will need to connect your main playback computer and your backup playback computer directly to your PlayAUDIO12 via USB-DAW connections instead of Ethernet. This is because the PlayAUDIO12 contains special circuitry that detects any playback problems and switches from the main playback computer to the backup playback computer automatically.
To ensure that your MIDI playback is handled correctly in this case you need to send MIDI from your computers directly to the PlayAUDIO12 via USB-DAW connections. Once the USB-DAW MIDI has been received by the PlayAUDIO12, the interface can then send it onwards via its Ethernet port to the main star network using RTP-MIDI.
For more information on the best way to configure a redundant RTP-MIDI system like this please see the Auracle User Guide chapter on Using the RTP-MIDI Manager.
Port limitations with a redundant PlayAUDIO12 system
It’s important to note that a redundant system like the one above does have one significant bottleneck. All of the MIDI coming from the computers has to pass through the PlayAUDIO12 before going to the Ethernet switch.
So that means that your MIDI network is effectively limited to the maximum number of RTP-MIDI ports that the PlayAUDIO12 is capable of supporting. That is 4 ports, each with 16 MIDI channels, for a total of 64 MIDI channels on your network.
So in a system like the above you could use 1 RTP-MIDI port to connect to each of the 3 MIDI interfaces on the right, and still have 1 left over; or you could assign 2 ports to one MIDI interface and 1 to each of the others.
So in a redundant system you do lose the ability to have an infinitely expandable network. However you gain the advantage of full redundancy, which is vital for live shows etc.