Measurement Computing DaqBook 2000 Series - Manual (Page 69)

DaqBook/2000 and DaqOEM/2000 Series 898695 Taking Measurements 8-7
Asynchronous I/O Operations
Each DaqBook allows asynchronous input of any counter or digital channel that is not currently configured
for synchronous acquisition. The circuitry allows for asynchronous output to any D/A channels that are
not currently configured for waveform output. Likewise, for DaqBook/2001, /2005 and DaqOEM/2001
and /2005 the 16-bit P3 [or JP3] digital port 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
(P2 or JP2, Port A, Port B, Port C)
The DaqBooks have an implemented Intel 8255 core in the digital I/O logic on the P2 port. 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
(P3 or JP3, Digital 0 through Digital 15) [Does not apply to DaqBook/2020]
The 16-bit P3 Digital Port can be used as either an input or output port. With this port, no configuration is
required. The port simply outputs when written to and inputs when read.
Expansion Digital I/O
The DaqBooks have the ability to expand their digital I/O capabilities via the P2 port and the connection of
applicable digital I/O expansion modules. These modules are discussed in the DBK
Option Cards &
Modules User’s Manual
(p/n 457-0905). 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
additional Intel 8255 ports as well as input isolation for applications that require the expanded capabilities.
Pulse Stream Output Using Timers (Timer0, Timer1)
Each DaqBook allows for 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.
For DaqBook/2020, the outputs are through BNC connectors labeled T0 and T1.
For DaqBook/2001 and /2005, the timer outputs are through the P3 connector, pin 15 for Timer 0 and pin
16 for Timer 1.
For DaqOEM/2001 and /2005, the timer outputs are through the JP3 header, pin 29 for Timer 0 and pin 31
for Timer 1.
Analog Output Channels
DAC0, DAC1, DAC2, DAC3
(AO0, AO1, AO2, AO3)
DaqBook/2020, DaqBook/2001, and DaqOEM/2001 can output analog data to any of the 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.
For DaqBook/2020, the analog out channels make use of BNC connectors labeled:
AO0, AO1, AO2, and AO3.
For DaqBook/2001, the analog out channels use P3 as follows:
DAC0 – P3 pin 34, DAC1 – P3 pin 33, DAC2 – P3 pin 32, DAC 3 – P3 pin 31.
For DaqOEM/2001, the analog out channels use JP3 as follows: DAC0 – JP3 pin 30, DAC1 – JP3 pin 28,
DAC2 – JP3 pin 26, DAC 3 – JP3 pin 24.