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Chapter 6. Service Request Function
6.18 SVC_REQ 17: Mask/Unmask I/O Interrupt
Use SVC_REQ 17 to mask or unmask an interrupt from an input/output board. When an interrupt is
masked, the CPU does not execute the corresponding interrupt block when the input transitions and
causes an interrupt.
The parameter block is an input parameter block only; it has a length of three words.
Address
0 = unmask input
1 = mask input
Address+1 memory type
Address+2 reference (offset)
Memory type is a decimal number that resides in the low byte of word address + 1. It corresponds to
the memory type of the input:
70 %I memory in bit mode
10 %AI memory
12 %AQ memory
Successful execution occurs unless:
▪
Some number other than 0 or 1 is entered as the requested operation.
▪
The memory type of the input/output to be masked or unmasked is not %I, %AI or %AQ memory.
▪
The I/O board is not a supported input/output module.
▪
The reference address specified does not correspond to a valid interrupt trigger reference.
▪
The specified channel does not have its interrupt enabled in the configuration.
6.18.1
Masking/Unmasking Module Interrupts
During module configuration, interrupts from a module can be enabled or disabled. If a module's
interrupt is disabled, it cannot be used to trigger logic execution in the application program and it
cannot be unmasked. However, if an interrupt is enabled in the configuration, it can be dynamically
masked or unmasked by the application program during system operation.
The application program can mask and unmask interrupts that are enabled using Service Request
Function Block #17. To mask or unmask an interrupt from an open VME module, the application logic
should pass VME_INT_ID (17 decimal, 11H) as the memory type and the VME interrupt id as the
offset to SVC_REQ 17.
When the interrupt is not masked, the CPU processes the interrupt and schedules the associated
program logic for execution. When the interrupt is masked, the CPU processes the interrupt but does
not schedule the associated program logic for execution.
When the CPU transitions from STOP Mode to RUN Mode, the interrupt is unmasked.
For additional information on configuring and using VME module interrupts in a PACSystems RX7i
control system, refer to PACSystems RX7i User's Guide to Integration of VME Modules, GFK-2235.
306
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
GFK-2950C
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