The NI-9145 operates in free-run mode or synchronized mode using the EtherCAT distributed clock (DC).

By default, free-run mode runs the conversion cycle at the rate of the slowest module. You can slow the free-run mode conversion cycle down by writing a minimum cycle time in nanoseconds to index 0x3001.1 of the NI-9145.

In synchronized mode, each conversion cycle begins with a signal from the EtherCAT master/scan engine. The NI-9145 procedures an error if the external cycle time is too fast for a module. NI Indcom for EtherCAT only supports synchronized mode.