Rockwell Automation 1747-PT1, D1747NP002 Hand-Held Terminal - Manual (Page 398)

Chapter 27
The Status File
27–30
Address Description 5/02
5/01,
Fixed
S:25
and
S:26
I/O Interrupt Pending
Read only. These two words are bit-mapped to the 30 I/O slots. Bit
S:25/1 through S:26/14 refer to slots 1–30. Bits S:25/0 and S:26/15
are reserved.
The pending bit associated with an interrupting slot is set when the
corresponding I/O slot interrupt enable bit is clear at the time of an
interrupt request. It is cleared when the corresponding I/O event
interrupt enable bit is set, or when an associated RPI instruction is
executed.
The pending bit for an executing I/O interrupt subroutine remains
clear when the ISR is interrupted by an STI or fault routine. Likewise,
the pending bit remains clear if interrupt service is requested at the
time that a higher or equal priority interrupt is executing (fault routine,
STI, or other ISR).
I/O interrupts are discussed in chapter 31.
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S:27
and
S:28
I/O Interrupt Enabled
Read/write. These two words are bit-mapped to the 30 I/O slots. Bit
S:27/1 through S:28/14 refer to slots 1–30. Bits S:27/0 and S:28/15
are reserved.
The default value of each bit is 1 (set). The enable bit associated
with an interrupting slot must be set when the interrupt occurs to allow
the corresponding ISR to execute. Otherwise, the ISR will not
execute and the associated I/O slot interrupt pending bit will become
set.
Changes made to these bits using the data monitor function or ladder
instructions other than IID or IIE of a programming terminal take affect
at the next end of scan.
I/O interrupts are discussed in chapter 31.
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S:29 User Fault Routine File Number
Read/write. You enter a program file number (3–255) to be used in all
recoverable and non-recoverable major errors. Program the ladder
logic of your fault routine in the file you have specified. Write a 0
value to disable the fault subroutine.
To provide protection from inadvertent EDT_DAT alteration of your
selection, program an unconditional MOV instruction containing the
program file number of your fault routine to S:29, or program a CLR
instruction at S:29 to prevent fault routine operation.
The user fault routine is discussed in chapter 29.
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