ADLINK PCI-7396 - Manual (Page 37)

Operation Theorem
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By using the four signals: P1C0, P2C0, P1C3, and P2C3, user can utilize
their combination to generate a proper IRQ for versatile applications.
4.3.5 Change of State (COS) Interrupt
What is COS?
The COS (Change of State) means when the input state (logic level) is
changed from low to high, or from high to low. The COS detection circuit will
detect the edge of level change. In the PCI-7396 card, the COS detection
circuit is applied to all the input channels. When any channel changes its
logic level, the COS detection circuit generates an interrupt request to PCI
controller.
COS Detection
The following timing is an example of COS operation. All the DI signals’ level
change will be detected and then take an ‘OR’ operation to generate the
INT1 or INT2 IRQ request.
If INT1 or INT2 IRQ request generates, the signal will be latched. User
should apply the function “_7396_CLR_IRQ” or “_7348_CLR_IRQ” to reset
its state, after the corresponding ISR is finished,
P2A0
COS
1
CO
S2
INT1
P1A0
Clear_IRQ Clear_IRQ Clear_IRQ