Principles of Operation
65
Note:
The USB LED, shown in
, blinks amber while the module is
acquiring data.
Filtering
The DT9828 module multiplexes all enabled channels to a single 24-bit Delta-Sigma
analog-to-digital converter (ADC). The overall throughput rate is programmable to up to
600 Samples/s. The throughput rate determines the ADC data rate, internal filter response,
and noise. The Delta-Sigma ADC noise is inherently low at all sample rates, but sampling at
lower rates yields lower noise. Additional noise filtering is implemented in software by a
moving average filter, which may be enabled or disabled in software.
The software filtering options are described as follows:
•
Moving average
– (The default filter setting.) This filter type removes unwanted noise
from your measurements and provides a compromise of filter functionality and response
time. This filter can be used in any application.
This low-pass filter takes the previous 16 samples, adds them together, and divides by 16.
•
None
– No filter (raw data). Use this option when you want to acquire fast thermocouple
response times. The response time is determined by the ADC data rate. Higher
throughput rates (data rates) yield faster response times, but the increased bandwidth also
results in higher noise.
Data Format
If you specify a thermocouple type of None for a thermocouple input channel, a voltage
measurement is selected and the instrument returns a voltage value. For all other
thermocouple types, a temperature value, in degrees C, or one of the error constants,
described on
, is returned.
In normal operation, one, 32-bit floating-point value is returned for each enabled channel. If
you enable the capability of returning CJC data in the data stream, described on
, two
floating-point values are returned in the data stream for each enabled analog input channel.
The first value in the pair represents the temperature (or voltage) of the channel; the second
value in the pair represents the CJC temperature (in degrees C) for that channel.
If the digital input port is in the channel list, that 4-bit value (value 0 to 15) is returned as float.
Note:
The Input FIFO stores up to 1024 samples.
Содержание DT9828
Страница 1: ...DT9828 User s Manual UM 24984 A Title Page ...
Страница 4: ......
Страница 8: ...Contents 8 ...
Страница 12: ...About this Manual 12 ...
Страница 13: ...13 1 Overview Features 14 Supported Software 16 Accessories 18 Getting Started Procedure 19 ...
Страница 20: ...Chapter 1 20 ...
Страница 21: ...Part 1 Getting Started ...
Страница 22: ......
Страница 23: ...23 2 Installing a Module Unpacking 25 Attaching Modules to the Computer 26 Configuring the Device Driver 29 ...
Страница 30: ...Chapter 2 30 ...
Страница 41: ...41 4 Verifying the Operation of a Module Selecting the Device 43 Thermocouple Measurement Example 45 ...
Страница 49: ...Verifying the Operation of a Module 49 ...
Страница 54: ...Chapter 4 54 ...
Страница 55: ...Part 2 Using Your Module ...
Страница 56: ......
Страница 57: ...57 5 Principles of Operation Analog Input Features 59 Digital I O Features 67 ...
Страница 80: ...Chapter 6 80 ...
Страница 86: ...Chapter 7 86 ...
Страница 87: ...87 8 Troubleshooting General Checklist 88 Technical Support 90 If Your Module Needs Factory Service 91 ...
Страница 92: ...Chapter 8 92 ...
Страница 106: ...Appendix A 106 ...
Страница 112: ...Appendix B 112 ...