Digital Input/Output Configuration for NI 9401

When you change the configuration of lines on a NI 9401 digital module between input and output, NI-DAQmx temporarily reserves all of the lines on the module for communication to send the module a line configuration command. For this reason, you must reserve the task in advance through the DAQmx Control Task before any task has started. If another task or route is actively using the module, to avoid interfering with the other task, NI-DAQmx generates an error instead of sending the line configuration command. During the line configuration command, the output lines are maintained without glitching.