Measurement Computing 2000 Series Daqboar - Manual (Page 31)

DaqBoard/2000 Series & /2000c Series User’s Manual 10-18-02 Daq Systems and Device Overviews 1-5
Synchronous Input Operations
The DaqBoard/2000 Series and /2000c Series products allow synchronous scanning and acquisition of
Analog Input, Digital Input and Counter Input Data at up to 200kHz aggregate scanning rates. The Analog
Input data can be either main unit or expansion modules from P1 compatible analog input modules. The
Digital Input data can be main unit 8-bit P2 (8255) digital inputs, 16-bit P3 digital inputs or P2 compatible
DBK digital input expansion modules.
Analog Input Channels
The DaqBoard/2000 Series boards and /2000c Series boards that offer analog input (see matrix) allow
analog input configuration for the board as well as the P1 compatible DBK analog input expansion
modules.
Channel Selection and Mode Settings
The main unit accepts up to 16 single ended or up to 8 differential-ended inputs and can be programmed for
single-ended or differential-ended on a per channel basis. Just one analog channel is sacrificed when a
DBK expansion module is enabled. See DBK documentation in the DBK Option Cards & Modules User’s
Manual (p/n 457-0905) for further information.
Channel Range and Polarity
Each main unit channel also may be programmed for either unipolar or bipolar mode with gain settings of
1,2,4,8,16,32 and 64.
Channel Sampling Interval
The DaqBoard/2000 Series and /2000c Series boards allow programmable sampling intervals of 5us or 10us
on a per channel basis. This mode allows some channels which change slowly but a higher degree of
accuracy is desirable to be sampled at a longer interval while channels that change more rapidly to be
sampled using a shorter interval. Each 5us or 10us interval reduces the maximum aggregate acquisition rate
for the entire scan by that amount.
Digital Input Channels
The DaqBoard/2000 Series and /2000c Series boards allow either synchronous scanning of digital input
channels or asynchronous I/O operations for all configured digital channels.
Counter Input Channels
The DaqBoard/2000 Series and /2000c Series boards allow synchronous scanning of the 4 16-bit counter
input channels. The four 16-bit counter channels can also be cascaded into two 32-bit counter channels.
For either cascaded or non-cascaded counter channels each channel can be configured for:
• Pulse Counting Mode – specifies that each counter should be cleared upon being read and placed into
the input scan.
• Totalize Counting Mode – specifies that each counter is to free-run and not be cleared during the input
acquisition.
Synchronous Input Acquisition Clocking
The DaqBoard/2000 Series and /2000c Series boards allow clocking of the synchronized inputs either by an
internal, programmable pacer clock or by external clocking. These products use a sequencer to implement a
multiplexing approach to gathering the input data. This means that with either internal or external clocking
the entire channel scan (including the sampling time for each channel) may not exceed the maximum
aggregate rate of 200kHz.