VME control using Lab Windows and VME-MXI-2
1) set the VME control signals SYSRESET and ACFAIL to both logic 1 and 0.
2) read/write memory addresses from the VME memory map.
I've not used VME before, and these don't look like trivial tasks. The VME rack is fitted with a VME-MXI-2 card and the PC is fitted with a PCI-MXI-2 card. If anyone has had experience of this before and pointers would be very useful. (I can't find much on the NI web site)
As for reading and writing memory addresses from the VME memory map, you could use functions such as viIn8, viIn16, viIn32, viOut8, viOut16, or viOut32 in the NI-VISA API. You can find the NI-VISA Funtion help at "Start >> Programs >> National Instruments >> NI-VISA >> NI-VISA Help" for Windows. Alternativelly, the NI-VISA Programmers Reference Manual is available for download from ni.com.
What exactly is your application that uses ACFAIL? ACFAIL is typically pretty unrealiable, and is a difficult signal to catch (especially over a bus extension like MXI-2). Basically, ACFAIL is asserted right before a total failure/shutdown of the chassis, so you have a very short window of time to detect the signal before it disappears.