National Instruments PC-TIO-10, User Manual

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Chapter 2 Configuration and Installation
© National Instruments Corporation 2-5 PC-TIO-10 User Manual
To disable the PC-TIO-10 interrupt request line, change the jumper setting as shown in Figure 2-
4.
W1
IRQ9 IRQ7 IRQ6 IRQ5 IRQ3 IRQ4
IRQ3 IRQ9
Figure 2-4. Interrupt Jumper Setting for Disabling Interrupts
Local Interrupt Selection
In addition to the jumpers for selecting the interrupt level used by the PC-TIO-10, a set of
jumpers, W2, is used to locally connect two of the counter outputs to the interrupt generation
circuitry. There are four positions on this set of jumpers: two No Connect positions (labelled
N.C.), a position for OUT2, and a position for OUT7. The position for OUT2 connects the
output of Counter 2 to the EXTIRQ1 input, while the position for OUT7 connects the output of
Counter 7 to the EXTIRQ2 input. The No Connect positions are intended as storage positions
for one or both of the jumpers if you do not want to use one or both of the counter outputs for
interrupt purposes. The default positions for the jumpers on W2 are shown in Figure 2-5.
W2
OUT2
OUT7
N.C.
N.C.
Figure 2-5. Local Interrupt Jumper Setting (Factory Setting)
OUT2 and OUT7 can be jumpered simultaneously. The interrupt for OUT2 is enabled and
disabled through access to the Port A interrupt-control circuitry of the MC6821 PIA. OUT7 is
enabled and disabled through access to the Port B interrupt-control circuitry of the MC6821 PIA.
One or both of these interrupts can be asserted at any time (if they are enabled). If both
interrupts are enabled simultaneously, your interrupt handler must check both channels for
interrupts before returning control to the foreground task. For more information, see Chapter 4,
Programming.