Can I do 8 bit change detection on port 1 or 3 of the pci-6534?

[Joe P.]

This should be a really easy question and I think I know the answer but I want to verify. Is it possible to do an eight bit acquisition on either port 1 or 3 of a PCI-6534 using change detection mode? The manual says to use either port 0 or 2. However, I would like to use those two ports for externally clocked buffered pattern input.

[Michael_S.]

Joe,

You will not be able to use ports 1 and 3 for change detection while ports 0 and 2 are being used for pattern input. This is because change detection is considered a "strobed" operation and the 6534 can do two strobed operations at a time. Pattern I/O is also considered to be a strobed operation. Basically, both of these operations make use of the internal clocks and the control lines (ie REQ pin).
If port 0 is using the control lines for pattern operations then you can not use them for change detection operations.

My only thought around this would be to do the following. Of your pattern input on ports 0 and 2 are see to read the digital lines at the same rate then you can make one 16-bit port (port 0,1) and read both ports at the same time using the REQ
1 control line.
Then you can set up another 16-bit port (port 2,3) and set that port for change detection.