Getting Started 17
Chapter 1
Setting the Interrupt
Priority
For most applications, the interrupt priority level should not need to be
changed. Interrupts are enabled at power-up, after a SYSRESET or after
resetting the module via the Control Register. An interrupt is generated after
any relay Control Register is accessed when interrupts are enabled. The
interrupt is generated approximately 1.3ms after one of the registers is
accessed.
The Interrupt Request Level switch selects the priority level to be asserted.
The Interrupt Request Level switch is set in position 1 when shipped from
the factory. The interrupts are disabled when set to level 0. Be careful when
deciding to disable the interrupts, as both the "VOLTMTR" and "SWITCH"
drivers require that interrupts be enabled.
To change the setting, rotate the switch so the arrow points to the interrupt
priority level desired. Interrupts can also be disabled using the E1476A
Status/Control Register. See Figure 1-6 for the Interrupt Request Level
switch.
NOTE
Some mainframes may require that backplane jumpers be set correctly for
each slot used. See the appropriate mainframe manual for details.
Figure 1-6. Setting Interrupt Request (IRQ) Priority
Level 0 = Interrupt Disabled
Interrupt Request (IRQ)
Level Rotary
Interrupt Request
Switch Location
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