Measurement Computing DaqBoard 1000 Series - Manual (Page 26)

1-4 Daq Systems and Device Overviews 889094 DaqBoard/1000 and /2000 Series User’s Manual
Synchronous Input Operations for DaqBoard/1000 and DaqBoard/2000 Series Boards
As indicated in the I/O matrix, applicable DaqBoards allow for synchronous scanning and acquisition of
Analog Input, Digital Input and Counter Input Data at up to 200kHz aggregate scanning rates.
For applicable DaqBoard/2000 Series devices, the Analog Input data can be either directly to the board or
from expansion analog input modules connected to P1. The Digital Input data can be to the board’s 8-bit
P2 (8255) digital inputs, 16-bit P3 digital inputs or P2 compatible DBK digital input expansion modules.
Refer to the applicable pinouts to see how P1, P2, and P3 relate to the 100-pin P4 connector.
DaqBoard/1000 Series boards do not support DBK options.
Analog Input Channels
The boards that offer analog input (see previous matrix) allow analog input configuration for the board.
For applicable DaqBook/2000 Series boards, analog input can be received from 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. In regard to DaqBoard/2000 Series boards,
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
DaqBoard/2000 Series board channels can be programmed for either unipolar or bipolar mode with gain
settings of 1,2,4,8,16,32 and 64. DaqBoard/1000 Series boards have the same gains but are only bipolar.
Channel Sampling Interval
The 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
Associated boards allow either synchronous scanning of digital input channels or asynchronous I/O
operations for all configured digital channels.
Counter Input Channels
Associated 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
Associated 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.