Chapter 5 Programming© National Instruments Corporation 5-11 SCXI-1120 User ManualTo program the hardscan circuitry, perform the following steps:1. Write binary 0000 0000 to the HSCR.2. Write binary 0000 1000 to the HSCR.3. Write the Slot 0 scan list to the FIFO.4. Write binary 0010 1100 to the HSCR.5. Write binary 101S 1100 to the HSCR.6. Write binary 101S 1110 to the HSCR.7. Write binary 101S 1111 to the HSCR.To program the hardscan circuitry to use the current scan list, perform the following steps:1. Write binary 0000 1000 to the HSCR.2. Write binary 0100 1000 to the HSCR.3. Write binary 0000 1000 to the HSCR.4. Write binary 0010 1100 to the HSCR.5. Write binary 101S 1100 to the HSCR.6. Write binary 101S 1110 to the HSCR.7. Write binary 101S 1111 to the HSCR.In the preceding steps:S = 0 if you want the scanning to repeat when the end of the list is reached.S = 1 if you want the circuitry to shut down after a single scan.When you are writing multiple entries to the same register, for example, repetitive writes to theHSCR or several FIFO entries, it is important that SS*13 or SS*14 go inactive (high) betweeneach entry. Select another slot or toggle the SLOT0SEL* line to temporarily deassert theappropriate SS* line.If consecutive scan list entries access an SCXI-1120, the module will reload theMUXCOUNTER with the starting channel after each entry. Thus, two entries with counts offour for one module will yield different behavior than one entry with a count of eight.For multiple-chassis scanning, program each Slot 0 with dummy entries to fill the sample countswhen the data acquisition board is accessing other chassis. Use Slot 13 as the dummy entry slot.See Example 3 at the end of this chapter.
