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Chapter 6. Service Request Function
6.28 SVC_REQ 32: Suspend/Resume I/O Interrupt
Use SVC_REQ 32 to suspend a set of I/O interrupts and cause occurrences of these interrupts to be
queued until these interrupts are resumed. The number of I/O interrupts that can be queued
depends on the I/O module's capabilities. The CPU informs the I/O module that its interrupts are to
be suspended or resumed. The I/O module's default is resumed. The Suspend applies to all I/O
interrupts associated with the I/O module. Interrupts are suspended and resumed within a single
scan.
SVC_REQ 32 uses only an input parameter block. Its length is three words.
0 = resume interrupt
Address
1 = suspend interrupt
Address + 1 memory type
Address + 2 reference (offset)
Successful execution occurs unless:
▪
Some number other than 0 or 1 is passed in as the first parameter.
▪
The memory type parameter is not 70 (%I memory).
▪
The I/O module associated with the specified address is not an appropriate module for this
operation.
The reference address specified is not the first %I reference for the High Speed Counter.
▪
▪
Communication between the CPU and this I/O module has failed. (The board is not present, or it
has experienced a fatal fault.)
Note: I/O interrupts, unless suspended or masked, can interrupt the execution of a function block.
The most often used application of this Service Request is to prevent the effects of the
interrupts for diagnostic or other purposes.
SVC_REQ 32 Example
Interrupts from the high speed counter
module whose starting point reference
address is %I00065 will be suspended
while the CPU solves the logic of the
second rung. Without the Suspend, an
interrupt from the HSC could occur
during execution of the third rung and
%T00006 could be set while %R000001
has a value other than 3,400.
(%AI00001 is the first non-discrete input
reference for the High Speed Counter.)
326
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
GFK-2950C
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