There are a couple of ways to add a DeviceNet device to your configuration:
Drag a revision from the DeltaV Explorer Library to the port under the DeviceNet card.
Right-click the port, select New DeviceNet Device, and browse for the revision.
When you add or delete a device placeholder, or change its address, you must download the port.
Use the device properties dialog (right-click the device and select Properties) to enable I/O polling, add a device description, set the device address, and modify the input/output sizes for this device only.