RTD/Target Catalog - RTD Embedded Technologies, Inc.

More documents

Recommendations

Info

Data Acquisition 101 Computer data acquisition involves converting real world signals such as position, temperature, or pressure into information a computer can understand. Any data acquisition board (DAQ) will give you lots of data. RTD’s DAQs not only collect data, they provide information. Information is what data acquisition is about; it means only collecting the data you want, when you want it. It is critical that you control when you take data, how much data you take, and have complete control over such parameters as timing, channel, gain, polarity, and triggering. RTD’s dataModules ® give you that control and the information you need. RTD Data Acquisition Modes RTD offers many acquisition modes by implementing a Channel-Gain table (CGT) that helps you get just the data you need. A CGT entry holds channel, gain, polarity, range, single-ended/differential, and skip bit information that is scanned at the full sampling rate of the DAQ. What makes a CGT so unique is that each channel can be programmed independently for sampling purposes with up to 8 K total entries in the table. Digital data markers can be collected and stored with the analog samples to identify your data accurately. Below are examples of RTD’s acquisition modes. Notice that all acquisition modes start with a trigger. TRIGGER SINGLE CONVERSION A single channel is sampled on each trigger SAMPLE TAKEN SAMPLED CHANNEL 1 1 1… TRIGGER MULTIPLE CONVERSIONS Pacer clock controls sample rate PACER CLOCK SAMPLE TAKEN SAMPLED CHANNEL 1 1 1 1 1 1 1 1 1… CHANNEL SCAN Randomly scans any channel at any gain TRIGGER PACER CLOCK SAMPLE TAKEN CHANNEL-GAIN TABLE ENTRY 1 2 3 4 5 6 7 8 9… BURST Triggers one channel/gain table scan TRIGGER BURST TRIGGER BURST CLOCK SAMPLE TAKEN CHANNEL-GAIN TABLE ENTRY 1 2 3 1 2 3 MULTI-BURST Triggers programmable number of channel/gain table scans TRIGGER PACER CLOCK SAMPLE COUNTER OUTPUT SAMPLE TAKEN To learn more about systems like the HiDANplus pictured here, turn to page 40. CHANNEL-GAIN TABLE ENTRY 1 2 3 1 2 3 1 2 3 1 2 3 24 “MIL Value for COTS Prices” | www.rtd.com
“Accessing the Analog World” Triggering If it is crucial to get the data you want, when you want it, then it follows that being able to communicate to your DAQ system which data you want is equally important. Triggering accomplishes this task. In fact, the more triggering options a board offers, the better the likelihood you will collect good data. RTD offers an abundance of triggering options that allow you to define how and when to capture data to ensure that you get the information you need. An oscilloscope is a specialized data acquisition system. If you let it run freely you will see lots of data. However, little information will be gained from the blur on the screen unless you use triggers. A trigger is an event happening. Some real world examples are when a pulse starts or ends, a warning light turns on or off, or an overload is detected. “Stackable, powerful, and optimized for success...” To get information from your DAQ you have to trigger it like an oscilloscope. There are three things that could happen when you get a trigger. A pre-trigger starts the DAQ, a post-trigger stops the DAQ, or an abouttrigger collects some data before and after the event. RTD’s many internal and external start, stop, and about trigger options give you all of these functions. Features of Start, Stop, and About Triggers Software External Digital Interrupt Timer/Counter Gated Sample Counter Sync Bus Trigger under software control Trigger on an external rising or falling edge Trigger when digital I/O matches a preset state or when any digital bit changes Trigger when a timer/counter expires Collect data when an external signal is active (signal can be either active low or active high) Trigger after a programmed number of samples have been collected Trigger multiple boards simultaneously This PC/104-Plus stack includes an AMD Geode LX cpuModule, a DSP Coprocessor, a 16-channel, 12-bit analog module with Autonomous SmartCal, and an 83 Watt power supply. Skip Bit Skip bits allow sampling different channels at different rates while maintaining accurate individual channel timing. The diagrams show how to sample channel 1 once every second and channel 4 once every three seconds. To take a set of eight samples, six from channel 1 and two from channel 4 (shown in the top diagram) make 12 entries into the channel-gain scan memory (bottom diagram) and set the pacer clock to run at 0.5 seconds. Four of the entries are skipped (skip bit set) and no A/D conversion is performed. Samples are not stored when they are not wanted, saving memory and eliminating the need to throw away unwanted data. PACER CLOCK A/D CONVERSION SAMPLED CHANNEL 1 1 1 4 1 1 1 4 skip 1 4 1 4 1 4 1 4 1 4 1 4 1 sec skip 1 sec skip 3 sec skip 1 sec 1 sec 1 sec 1 sec RTD Embedded Technologies, Inc. | 2010 Product Guide 25
Page 1 and 2: RTD Embedded Technologies, Inc. Boa
Page 3 and 4: Table of Contents RTD: Complete In-
Page 5 and 6: A Broad Range of Solutions From RTD
Page 7 and 8: “Accessing the Analog World” Ma
Page 9 and 10: “Accessing the Analog World” Th
Page 11 and 12: Solid Engineering “Accessing the
Page 13 and 14: “Accessing the Analog World” In
Page 15 and 16: “Accessing the Analog World” In
Page 17 and 18: “Accessing the Analog World” PC
Page 19 and 20: “Accessing the Analog World” No
Page 21 and 22: “Accessing the Analog World” 80
Page 23: RTD Flies High with NASA “Accessi
Page 27 and 28: dataModules ® “Accessing the Ana
Page 29 and 30: Real Time Data Logging “Accessing
Page 31 and 32: Motion Controllers “Accessing the
Page 33 and 34: Frame Grabbers “Accessing the Ana
Page 35 and 36: Wireless Telematics “Accessing th
Page 37 and 38: “Accessing the Analog World” Co
Page 39 and 40: Development Tools “Accessing the
Page 41 and 42: Selected Application Highlights “
Page 43 and 44: IDAN ® Systems “Accessing the An
Page 45 and 46: HiDANplus Systems “Accessing the
Page 47 and 48: RTD IDAN ® an Integral Part of Ast

RTD/Target Catalog - RTD Embedded Technologies, Inc.

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?