low rates of (modulus) breakpoint re-enabling

[stde]

Hello!

I am using the motion control NI7334 and I need the breakpoint output to trigger my measurements.

In a quite simple program I re-enable the (modulus) breakpoint each time it occurred. The fastest repetition rate I could generate to enable the breakpoint was about 110 Hz, with higher breakpoint frequencies it becomes irregular, means I don't get all breakpoints. I'm worried if it becomes even worse when my program will be more complex. These low rates for re-enabling the breakpoints are a problem of the labview-code, of windows xp or of the communication between software and PCI-board? 

[Jochen]

The reason why you can't reach faster breakpoint reenable rates is a mixture of all the reasons that you have suggested plus some internal delays on the board. There is not much you can do about that.
There are several options for better breakpoint performance:

1. You could contact your local NI branch to upgrade your NI 7334 to a NI 7354. The 735x boards provide buffered breakpoints with 2 kHz trigger rate and periodic breakpoints with 4 MHz. Reenabling is done automatically on the board.
2. You could use the counter inputs of a DAQ-board like the PCI-6220 (two counters) or a dedicated counter board like the PCI-6601 (four counters) to generate the trigger signals by dividing down the frequency of the encoder signals. As this runs in hardware, you will also be able to generate triggers with rates up to several MHz.

I hope that helps,

Jochen Klier
National Instruments Germany