Output devices take data and write it out to external devices to control them based on 3D models in the scene.

An output device is more complex than an input device because it must have both input and output nodes to be evaluated in the correct order with the correct information.

An output device with two outputs (driving two values on a piece of hardware) needs two input animation nodes, two output animation nodes, and two pieces of data in MotionBuilder to drive the device’s inputs. The data from MotionBuilder is pumped through the device and the connection is made between the inputs and outputs of the device (which can be represented as a box). This information on the output connectors of the device (box) is then written to the hardware.

In the case of an output device, a regular clock cycle is as follows:

1. DeviceIONotify is called at the SamplingPeriod.
2. Writes the data from the hardware abstraction to the hardware itself.
3. DeviceEvaluation is called at the SamplingPeriod rate.
4. Writes the data from the output node to the hardware abstraction.
5. AnimationNodeNotify is called when it is needed.
6. Write the data from the input node (model binding) to the output node.
7. It is called by DeviceEvaluation to evaluate the output node before the data is read.