NuDAQ PCI-8554, Руководство пользователя

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Introduction
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Introduction
PCI-8554 is a general-purpose counter / timer and digital I/O card.
This card have four 8254 chips on board, so it provides twelve 16
bits down counter or frequency dividers.
This card has multi -configurations. The counters can be set as
independent counter or cascaded counter. The gate control of
counter come from either external source or internal default enable
signal. The clock source of the counters can be set as internal or
external clock source, when external clock is used, user can set the
jumper to decide whether the debounce function is used or not used.
An 8 MHz crystal is used as internal clock source. It is possible to
use this card on variety of powerful counter / timer functions to match
your industry and laboratory applications. Users can set the
configuration to fit the variety of applications.
The card also provides digital output and input port. There are 8 bits
digital output and 8 bits digital input channels which can be used to
control or monitor the external devices.
PCI-8554 provides one interrupt signal which comes from internal or
external interrupt sources, the internal interrupt sources come from
the counter output. The interrupt can be used for watchdog timer or
others applications. The maximum interrupt time interval can be 536
sec.
The I/O signals are via a 100 pin SCSI-II connector that project
through the computer case at the rear of the board. The figure 1.1
shows the block diagram of the PCI-8554.