User`s guide

Universal Library User's Guide Counter Boards - USB-4300 Series
172
PortType AUXPORT*
BitNum 0 to 7
* AUXPORT is not configurable for these boards.
Event notification
Event notification functions and methods supported
UL: cbEnableEvent(), cbDisableEvent()
UL for .NET: EnableEvent(), DisableEvent()
Event notification argument values
EventType ON_EXTERNAL_INTERRUPT
EventParameter LATCH_DI, LATCH_DO
LATCH_DI can only be used with cbDIn() and cbDBitIn(). LATCH_DO can only be used with cbDOut() and
cbDBitOut().
Hardware considerations
Clock input frequency
The clock speed is configurable with InstaCal for 1 MHz, 1.67 MHz, 3.33 MHz, or 5 MHz.
Event Notification
ON_EXTERNAL_INTERRUPT can't be used with cbCStoreOnInt() or CStoreOnInt().
Interrupt Input pin
You can configure the interrupt input pin (INT) with InstaCal to trigger off rising or falling edge inputs. You
can program this pin to perform the following tasks:
 Send an event notification to the computer. The transfer rate is system-dependent.
 Latch digital input data.
 Latch digital output data.
 Save the current value of a counter. You can configure this option for each counter individually.
Digital bit latching
Digital input bit latching is supported by cbDIn() and cbDBitIn(). Digital output bit latching is supported by
cbDOut() and cbDBitOut().
 Use the EventParam option LATCH_DI with cbDIn() and cbDBitIn() to return the data that was latched in
at the most recent interrupt edge. The current value of the digital inputs (0 or 1) is read and stored. The
stored value is updated when an active edge occurs on the Interrupt Input pin.
There is a latency period between when an active interrupt edge occurs on the INT pin and when the
action triggered by that interrupt occurs. This latency can be as long as 100 µs, but typically varies from
about 9 µs to about 40 µs between interrupts.
 Use the EventParam option LATCH_DO with cbDOut() and cbDBitOut() to latch out the data most
recently written to the device. The digital outputs are not set to the value written until an active edge
occurs on the Interrupt Input pin.