Master Timebase Signal

The Master Timebase (MasterTimebase) signal, or Onboard Clock, is the timebase from which all other internally generated clocks and timebases on the board are derived. It controls the timing for the analog input, analog output, and counter subsystems. It is available as an output on the I/O connector, but you must use one or more counters to do so.

The maximum allowed frequency for the MasterTimebase is 20 MHz, with a minimum pulse width of 23 ns high or low. There is no minimum frequency limitation.

The two possible sources for the MasterTimebase signal are the internal 20MHzTimebase signal or an external signal through RTSI 7. Typically the 20MHzTimebase signal is used as the MasterTimebase unless you wish to synchronize multiple devices, in which case, you should use RTSI 7. Refer to Real-time System Integration Bus for more information about which signals are available through RTSI.

The following figure shows the timing requirements for MasterTimebase.