Labview 7.0 Synchronise Tasks

[MattA1]

Hi forum,

I'm trying to get two DAQ tasks to go at exactly the same rate and start at exactly the same time.

One task is sampling data on an analog in channel, while the other is providing a clock both for a

separate external system and for the sampling task. I am using the PCI board NI-6221 and a SCB-68

connector block. The Ctr1 out terminal (PFI13) is also physically wired to the Ctr0 source terminal (PFI8).

What I have so far is in the attached VI, based on one of the LV7.0 shipping examples, but it doesn't

quite work right.

1. The data acquisition always seems to go too slow, as I get error -200248 (I think it was) about the samples not being available yet for the "Read" node.
2. On the external system, I can see how many pulses have been received and it doesn't seem to match up to the total number required to be sent, even after the clock task has finished.
3. I'm not sure I have the right method for synchronising the tasks; what I really want to happen is that for every individual pulse sent out by the clock task, the read task acquires 1 sample.

If anyone could help me with these 3 problems, or suggest other ways to achieve this goal, I'd very much appreciate it.