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PCI-DIO-48 - PCI Digital I/O 48-ch

Acces I/O



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Product Datasheet

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The PCI-DIO-48/48S, PCI-DIO-48JP/JPS, PCI-DIO-48JPL/JPLS, PCI-DIO-48H/HS and PCI-DIO-24S are 24- and 48-bit parallel digital input/output cards designed for use in PCI-Bus computers. The card is 6.9 inches (175 mm) long and may be installed in any 5-volt PCI slot in IBM and compatible computers.

The 48J/48JS cards use a 68-pin SCSI-type connector, while the 48H/48HS cards use a 100-pin SCSI-type connector. The 48JP/48JPS cards use a 68-pin SCSI-type connector which is pin-in-socket, and has jack-screws provided as a means to retain the mating cable. The 48JPL/48JPLS cards use the 68-pin SCSI-type pin-in-socket connectors; however one-touch latches are used instead of jack screws. The 48/48S cards use 50-pin headers on the face of the board, as well as the 24S card which is simply a depopulated 48S card.

The cards contain two Programmable Peripheral Interface chips type 8255-5 (PPI) to provide computer interface to the 48 I/O lines. Each PPI provides three 8-bit ports A, B and C. Each 8-bit port can be software configured to function as either inputs or latched outputs. Port C can also be configured with four inputs and four output latches.

Each I/O line is buffered and capable of sourcing 15 mA or sinking 24 mA (64 mA on request). Tristate I/O line buffers are configured automatically by the hardware logic for input or output use according to a direction control signal from the control register in the PPI. Pull-ups on the card assure that there are no erroneous outputs at power up until the card is initialized by system software.

These cards use one address space, and occupy 16 consecutive register locations. When the card is first installed, Windows will detect it as new hardware and assign it an IRQ number and base address. There are no switches to set or base addresses to assign, making it easy to use. You cannot set or change the card's base address, you can only determine what the system has assigned. The PCI Bus supports 64K of I/O address space so your card inchs address may be located anywhere in the 0000 to FFFF range.


The distinguishing feature for the "48S" model is that the state of all inputs can be monitored and if one or more of the bits change states, a latched interrupt request can be generated. Therefore it is not necessary to use software polling on the inputs to detect a change of state condition. The change-of-state interrupt is enabled by a software write command to an interrupt-enable register. Once latched, the change-of-state interrupt can be cleared by a software write.

The C3 bit on either 24-bit port can be used as an external interrupt to the computer if interrupt enable (IEN) jumpers are installed. When C3 is level triggered, an interrupt is requested. Interrupts from the two ports are OR'ed together with any change-of-state interrupt. The interrupts are assigned by the system.