Thank you for the fast reply!
I am using the onboard port-- no PCI cards are installed. The port does not seem to be outputting correctly; using a voltmeter, I get a constant 3-5V on pins 1-4, 7, & 8, regardless of whether I am jogging or not, and regardless of pin assignment in the Ports and Pins configuration menu (many variations tried).
Is there a way to test Port assignment? I would expect the default to be adequate with no other options available...
Regarding the Estop, I am using it with the Estop set to 'Emulation' and 'Active low'. (no Estop is actually hooked up)