Hi cws6805,
Thank you for contacting National Instruments. The DTACK signal is commonly used to handle interrupts. If you are using the DTACK signal for interrupts, then I recommend you simply handle the interrupts. There is a pretty good example in LabVIEW 6.1 that explains how to use VISA to handle VXI interrupts. To find this example, open LabVIEW 6.1 and select Find Examples. Select Hardware Input and Output >> VISA >> VXI/VME Interrupt Event Handler.vi.
The VME-MXI-2 is a VXIbus controller, not a VXIbus analyzer. This means it has the ability to control the bus, but it does not have the functionality to pass all bus information to your PC. If you want to know when that line is high and when it is low, you will need to use another instrument that ca
n analyze the bus. You could use a third party bus analyzer, or you could use any Digital Multimeter (DMM). I suggest you connect the DTACK line to a DMM and monitor the voltage. The DTACK line is on Pin 16, Row A of the J1 connector.
Regards,
David Shatila
Applications Engineer
National Instruments
