DNx-AI-208 Analog Input Layer
Chapter 3
10
Programming with the Low-Level API
Tel: 508-921-4600
www.ueidaq.com
Vers:
4.6
Date: November 2013
File:
AI208 Chap3.fm
© Copyright 2009
United Electronic Industries, Inc.
3.2
Channel List
Settings
Bit
Name
Purpose
Macro
31
DQ_LNCL_NEXT Tells firmware that there is
a “Next Entry” in the
channel list
20
DQ_LNCL_TSRQ Request timestamp as the
next data point
11..8
Gain
DQ_LNCL_GAIN()
7..0
Channel number
The AI-208 layer has a very simple channel list structure, as shown below:
Gains are different for different options of the AI-208 layer, as listed in the follow-
ing table.
NOTE:
The Minimum Allowed Settling Time is the shortest time for which the
firmware allows a channel to settle. When the scan rate and channel are
programmed, the firmware allocates the minimum time for each channel
depending on the gain selected, and then stretches the settling time as
much as possible to utilize at least 2/3 of the time between scan clocks.
3.3
Layer-
specific
Commands
and
Parameters
The AI-208 layer has a number of layer-specific functions, as follows.
•
DqAdv208Read
This function uses
DqReadAIChannel()
but converts data using
internal knowledge of the input range and gain of every channel.
When this function is called for the first time, the firmware stops any
ongoing operation on the device specified and reprograms it in
accordance with the channel list supplied. This function uses the
preprogrammed CL update frequency – 10Hz. You can reprogram the
update frequency by calling the
DqCmdSetClk()
command after the
first call to
DqAdv208Read()
.
Layer type
Range
Gain
Gain
Number
Min. Allowed
Settling Time,
us
AI-201-208
±10V
1
0
40
±5V
2
1
50
±2.5V
4
2
60
±1.25V
8
3
70
±1V
10
4
80
±500mV
20
5
100
±250mV
40
6
120
±125mV
80
7
140
±100mV
100
8
160
±50mV
200
9
180
±25mV
400
10
200
±12.5mV
800
11
220
