It depends on the type of digital task. You can have any number of non-timed (static) digital tasks on an M-Series board. You can also have timed (correlated) tasks. They are called correlated because there is not seperate timing engine to generate the clock for the task. You need to specify a clock source which can be internal or external to the board. A common practice is to use the analog input or analog output sample clock (thus correlating your data) or to use one of the on board counters to generate a pulse train and use that output as the digital clock. You are limited to one correlated input and one correlated output task.
So quick summary:
No limit on non-timed digital tasks.
1 correlated input task.
1 correlated output task.
Hope that helps,
Mark
