Data ports relay data to and from the Multirate diagram, similar to control and indicator terminals on a VI diagram. Unlike terminals on a VI diagram, data ports relay data in streams as long as the ports receive data.
In a VI targeted to the host or controller, you can input only arrays of data to a Multirate diagram and output only arrays of data from a Multirate diagram. When you input an array to a Multirate diagram from a VI, LabVIEW converts the array to a stream because the Multirate diagram operates on data streams. If you input a two-dimensional array to a Multirate diagram, LabVIEW converts the two-dimensional array to a stream array. Likewise, if you output a stream scalar or a stream array from a Multirate diagram to a VI, LabVIEW converts the stream scalar to an array and the stream array to a two-dimensional array in which each row in the array is a data point.
The Multirate Diagram node behaves differently in a VI targeted to an FPGA than in a VI targeted to a host. If you call a Multirate diagram from a VI targeted to an FPGA, the Multirate Diagram node outputs a FIFO reference for each port on the Multirate diagram, including input ports.