When you have a question about process automation that needs a short answer, let us know with #WishIknew and @Visaya! We’ll reply with a #WishIknew post. It’ll give a quick explanation, then some related articles, videos, or reviews if you want to know more.

I wish I knew what the DeviceNet topology is!

You can structure your network in many ways for DeviceNet, but you need to know how it works to stay within its limits. Simply put, DeviceNet uses a trunkline-dropline topology on a loop-powered network with 24 volts of direct current and 8 amps.

The loop-powered aspect of it means that you can power some low-energy devices directly. If a device needs more juice than the network can offer, then you can hook that device up to an external power supply and just use the network to communicate.

Keep in mind also that the network length will vary with the network speed and type of cable. For instance, if you have a flat cable, the trunk distance for a baud rate of 125 kilobytes per second (Kbps) will have to stay within 420 meters. So 250 Kbps needs 200 meters, and 500 will go to 75 meters. You can choose round thick cable, round thin cable, or others to change these numbers.

You can configure the drop lines in several ways, as you can see in the graphic. But remember – keep your drop lines thinner than your trunk line.

When you have to size a new DeviceNet network, you can use some simple equations to set up. But you’ll need your cable type, device energy consumption, current, and other specs to do the math.

You can find other #WishIknews on DeviceNet here.

Recommended articles