Detailed descriptions
16.2 Bus board
SIMATIC Rack PC 840 V2
16-14
Operating Instructions, Edition 05/2006, A5E00248055-04
16.2.2
Exclusive PCI hardware interrupt
Applications demanding a high-performance interrupt require a high-speed hardware
interrupt reaction. The PCI hardware interrupt should be used only by one resource in order
to ensure high-speed reaction of the hardware. This can be forced by appropriate setting in
the system BIOS.
Setting up a reserved interrupt on the device
A reserved interrupt can only be set and used for PCI Slot 2 or 6 and 4. Further reserved
interrupts for use on the slots are not available.
An exclusive interrupt cannot be used on any of the PCI slots in the basic configuration. In
order to set up a reserved interrupt, you first need to disable the functions on the
motherboard*. This is possible for PCI slots 2 and 4.
In order to set up a reserved interrupt on PCI slot 2 or 6, you need to disable USB Controller
B (this is the upper USB port of the motherboard) in the BIOS.
In order to set up a reserved interrupt on PCI slot 4, you need to disable USB 2.0 Controller
(all USB ports are now operating in USB 1.1 mode) and, if installed, the PROFIBUS.
* For information on how to disable motherboard functions, refer to the chapter dealing with
the BIOS Setup "Advanced Menu".
Assigning a reserved interrupt in the BIOS Setup
With the factory setting of the system BIOS, the interrupts are automatically assigned to the
slots.
Depending on the system configuration, several slots may be assigned the same interrupt.
Here we refer to interrupt sharing.
In the BIOS Advanced Menu interrupts can be set to reserved and be assigned to the
interrupt lines of the slots. Here we refer to a reserved interrupt.
To do so:
To enable the use of a reserved interrupt at PCI slot 2 or 6, assign PCI IRQ Line 2 to the
required free interrupt, and all other PCI interrupt channels (channels 1, 3, 4) to another
interrupt.
To enable the use of a reserved interrupt at PCI slot 4, assign PCI IRQ Line 4 the required
free interrupt, and all other PCI interrupt channels (channels 1, 2, 3) another interrupt.
To do this, open the Advanced menu of the BIOS setup and then PCI Configuration. In this
menu you can assign the specific PCI IRQ channels to the respective interrupts.
You cannot assign interrupts that are already used by the system.
If a pre-assigned or reserved interrupt is assigned manually, it is indicated with a yellow star.
This means it cannot be used.
Interrupts not reserved by the system can be assigned twice.
