Interrupt Assignments - Siemens SIMATIC PG 720 P Manual

Hardware Information
8.2

Interrupt Assignments

Interrupt
The PG 720 uses the two integrated interrupt controllers of type 82C59 to handle
Assignment the 16 hardware interrupts (IRQ 0 to IRQ 15).
The INT output of the slave controller is connected to the IRQ 2 input of the
master controller. Interrupt 9 (IRQ 9) can be used on the bus for the assigned
interrupt 2 (IRQ 2). In the initialization phase, IRQ 9 is assigned to the software
interrupt vector 0A H (IRQ 2) by the ROM-BIOS.
Priority The priority of the interrupts is in the reverse order of their numbering. This
means the following:
I/O Addresses of
the Interrupt
Controllers
SMI
NMI
IRQ 0
IRQ 1
IRQ 2
IRQ 3
IRQ 4
IRQ 5
IRQ 6
IRQ 7
IRQ 8
IRQ 9
IRQ 10
IRQ 11
IRQ 12
IRQ 13
IRQ 14
IRQ 15
Note the interrupts which are already occupied in the system.
8-6
Interrupt IRQ 0 has the highest priority and interrupt IRQ 7 the lowest.
For triggering IRQ 2, interrupt IRQ 8 has the highest and IRQ 15 the lowest
priority. Interrupts IRQ 8 to IRQ 15 therefore have higher priority than
interrupts IRQ 3 to IRQ 7.
The interrupt vectors are initialized and masked when the PG 720 is powered
up.
Interrupt
System management interrupt, cannot be masked
Expansion slots signal I/O channel check 2
Internal timer (system clock)
Keyboard
Cascading from interrupt controller 2
Serial port 2 (COM2/IrDA) [can be enabled in setup]
Serial interface 1 (COM1/TTY) [can be enabled in
setup]
MPI port [can be enabled in setup]
Floppy controller
Parallel port 1 (printer port LPT 1/EPP/ECP)
[can be enabled in setup]
Battery-backed real-time clock (RTC)
VGA controller [generally not used]
Free or PCMCIA driver
Free or PCMCIA driver
PS/2 mouse or trackball in keyboard.
Can be enabled in setup if mouse/trackball function is
not required.
Math coprocessor error
IDE interface
Free or PCMCIA driver
Description
PG 720 P Programming Device
C79000-G7076-C721-02
Assigned
Interrupt
Vector,
Memory
Address
–
INT 2 H
INT 8 H
INT 9 H
INT A H
INT B H
INT C H
INT D H
INT E H
INT F H
INT 70 H
INT 71 H
INT 72 H
INT 73 H
INT 74 H
INT 75 H
INT 76 H
INT 77 H