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Measurement Computing DaqBook 2000 Series User Manual

Page 21

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DaqBook/2000 Series and DaqOEM/2000 Series

898095

Device Overviews 2-5

Asynchronous I/O Operations

The DaqBook/2000 Series and DaqOEM/2000 Series devices allow asynchronous input of any counter or

digital channel that is not currently configured for synchronous acquisition. The devices also allow for

asynchronous output to any D/A channels not currently configured for waveform output. Likewise, the

16-bit P3 digital port, if available, can be used for both asynchronous input and output operations. In

addition, the timer outputs can be programmed at any time regardless of the current state of synchronous or

asynchronous operations on other channels.

Digital I/O Channels

Local 8255 Channels

The DaqBook/2000 Series and DaqOEM/2000 Series devices have an implemented Intel 8255 core in the

digital I/O logic on the P2 port of the product. With the Intel 8255 there are three 8-bit wide ports

available for I/O and one 8-bit wide port for configuration purposes. The configuration port is used to

configure the other three 8-bit ports for either input or output operations.

Local 16-bit P3 Port

The 16-bit P3 Digital Port can be used as either an input, or an output port. With this port, no

configuration is required, the port simply outputs when written to and inputs when read.

The 16-bit P3

port does not apply to DaqBook/2020

.

Expansion Digital I/O

The DaqBook/2000 Series and DaqOEM/2000 Series devices have the ability to expand digital I/O through

the P2 port via digital I/O expansion modules. These modules are discussed in the DBK

Option Cards &

Modules User’s Manual

. When using the digital I/O expansion modules the local P2 Intel 8255 digital I/O

becomes inaccessible in lieu of the expansion modules. These expansion modules provide additionally

Intel 8255 ports as well as input isolation for applications that require the expanded capabilities.

Pulse Stream Output Using Timers

The DaqBook/2000 Series and DaqOEM/2000 Series devices allow the generation of output pulses based

upon a programmable setting. These output timers can be set at any time regardless of the state of any

synchronous or asynchronous operations which are currently taking place on other channels.

Analog Output Channels

The DaqBook/2001, DaqOEM/2001, and DaqBook/2020 have the ability to output analog data to any of

the available (up to four) D/A channels. Each D/A channel may be asynchronously updated by an

application if the D/A channel is not currently being used for waveform output operations. DaqBook/2005

and DaqOEM/2005 do not have analog output capability.

Counter Input Channels

The DaqBook/2000 Series and DaqOEM/2000 Series devices have counter input capabilities and have the

ability to read counter input [if the counter channel is not configured for synchronous acquisition]. As in

the case of synchronous operations the 4 16-bit counter input channels can be used individually or

cascaded into two 32-bit counter channels. For either cascaded or non-cascaded counter channels each

channel can be configured for:

Clear on Read Mode

- specifies that each counter should be cleared (reset to 0) upon being read.

Continuous Totalize Mode

– specifies that each counter is to free-run and not be cleared during

the read operation.

This manual is related to the following products: