The DVRT-Link™-LXRS® is a specialized node designed for high performance data acquisition from inductive displacement sensors including all of the LORD MicroStrain® DVRT sensors.

Product Highlights

  • Designed for a wide range of inductive displacement sensors including all LORD MicroStrain DVRTs
  • Wireless technology and a rechargeable battery make the DVRT-Link®-LXRS® ideal for remote, long-term monitoring of micro-miniature displacement measurements.
  • User-programmable sample rates up to 4096 Hz
  • Simultaneously transmit real-time data and log to memory

Datasheet Software

Wireless Simplicity, Hardwired Reliability

High Performance

  • Node-to-node synchronization up to ±32 microseconds
  • Scalable, long range wireless sensor networks up to 2 km
  • Lossless data throughput under most operating conditions

Ease of Use

  • Low power consumption allows extended use.
  • Remotely configure nodes, acquire and view sensor data with Node Commander®.
  • Optional web-based SensorCloud™ interface optimizes data storage, viewing, and analysis.
  • Easy integration via comprehensive SDK

Cost Effective

  • Out-of-the box wireless sensing solution reduces development and deployment time.
  • Volume discounts

General

Sensor input channels

Inductive displacement sensor,1 channel

Integrated sensors

Internal temperature, 1 channel

Data storage capacity

2 M bytes (up to 1,000,000 data points, data type dependent)

Displacement Sensor Input

Sensor excitation

Regulated sine wave, 150 kHz standard

(other frequency options available)

Low-pass filter

250 Hz standard (factory configurable 10 Hz – 20 kHz)

Resolution

12 bit

Signal-to-noise ratio

1,000 to 1 typical

(factory calibrated with DVRT® sensor)

Integrated Temperature Channel

Measurement Range

-40 °C to 85 °C

Accuracy

± 2 °C (at 25 °C) typical

Sampling

Sampling modes

Synchronized, low duty cycle, datalogging

Sampling rates

Continuous sampling: 1 sample/hour to 512 Hz

Periodic burst sampling: 32 Hz to 4096 Hz

Datalogging: 32 Hz to 4096 Hz

Sample rate stability

± 3 ppm

Network capacity

Up to 2000 nodes per RF channel (and per gateway) depending on the number of active channels and sampling settings. Refer to the system bandwidth calculator: http://www.microstrain.com/configure-your-system

Synchronization between nodes

± 32 μsec

Operating Parameters

Radio frequency (RF)

transceiver carrier

2.405 to 2.470 GHz direct sequence spread spectrum over 14 channels, license-free worldwide, radiated power programmable from 0 dBm (1 mW) to 16 dBm (39 mW); low power option available for use outside the U.S.A.- limited to 10 dBm (10 mW)

RF communication protocol

IEEE 802.15.4

Range for bi-directional RF link

70 m to 2 km line of sight with RF power setting

Power source

Internal: 3.7 V dc, 250 mAh rechargeable Lithium polymer battery

External: 3.2 V dc to 9.0 V dc

Power consumption

See power profile : http://files.microstrain.com/DVRT-Link- LXRS-Power-Profile.pdf

Operating temperature

-20 ˚C to + 60 ˚C (extended temperature range available with custom battery and enclosure, -40 ˚C to + 85 ˚C electronics only)

Maximum acceleration limit

500 g standard (high g option available)

Physical Specifications

Dimensions

61 mm x 61 mm x 27 mm

Weight

58 grams

Enclosure material

ABS plastic

Integration

Compatible gateways

All WSDA® base stations and gateways

Compatible sensors

All LORD MicroStrain DVRT® sensors. Other inductive displacement transducers possible (contact LORD MicroStrain Technical Support)

Connectors

LORD MicroStrain DVRT® sensor connector

Sensor warm-up time

30 seconds recommended

Software

SensorCloud™, Node Commander®, WSDA® Data

Downloader, Live Connect, Windows XP/Vista/7 compatible

Software development

Open-source MicroStrain Communications Library (MSCL) with sample code available in C++,Python,and.NET formats (OS and computing platform independent): http://lord-microstrain.github.io/MSCL/

Regulatory compliance

FCC (U.S.), IC (Canada), ROHS

 

In general 802.15.4 and WiFi (802.11) coexsist without much interference to either type of signal.  However, physical placement of wireless routers and WSDA -base stations may require the selection of "prefered" channels.   There are only two (2) 802.15.4 channels where WiFi DOESN’T share the same frequency, 15 and 20.

Typically, Wifi APs default to channel 6.

 

*note: channel 25 and 26 are not available with current Lord Microstrain wireless technology

The % bandwidth has to do with how many nodes/channels you can use at one time.  When setting up a Synchronized Sampling network, Node Commander will interrogate each node and assign transmission slots for them to send data to the base station.  This is designed to keep the nodes from broadcasting at the same time and causing data loss.  The more channels, and higher sample rate of a node will require more transmission slots, thus higher % of available bandwidth used.

Excel displays our time stamp incorrectly.  If you were to open the data file in Notepad you would see the correct time format.  To correct the data in Excel, Highlight all of column A, right click on the highlighted region and select Format Cells.  Under the Number tab select Custom, Scroll to the bottom of the list that appears and select “m/d/yyyy h:mm”.  You will need to add “:ss.000” to the end of this, so it looks like this “m/d/yyyy h:mm:ss.000” .  Setting the cells to this will give you the highest resolution that Excel can show.

We use Universal Coordinated Time (UTC) to collect data on all of our devices.  There is no provision to set the time to a local time zone. 

In Node Commander software, on the analog pairing screen, there is a check box for "Float". What is the function of this check box?

 

 

 

If the node is configured to send data to the base station in floating point mode, you need to enable this checkbox and set the 0-3 volt scaling.

 

The WSDA-RGD (with internal GX3 inertial sensor) is configured to produce the following messages on startup.

GPS Data (1 Hz):

  • UTC Time
  • LLH Position
  • NED Velocity

AHRS Data (100 Hz):

  • Euler Angles

From this output the WSDA logs:

GPS (1 Hz):

  • latitude
  • longitude
  • height above ellipsoid
  • height above MSL
  • horizontal accuracy
  • vertical accuracy
  • speed

AHRS (100 Hz):

  • roll
  • pitch
  • yaw

The WSDA-RGD does not log any data until it gets a valid time, if it is set to get time from GPS only it will not log any output from the GX3 until the UTC timestamp from the GX3 is valid, even though the GX3 is producing valid AHRS data.

This data is not user configurable and is not available as a live stream through LiveConnect.

As a general rule, you can calculate the battery life of a wireless node by dividing the amp hours of charge on the battery by the amps consumed during sampling.

Using the V-Link-LXRS as an example, we read in the data sheet (http://files.microstrain.com/V-Link_LXRS_datasheet.pdf) that the internal rechargeable battery has a nominal charge of 650 mAh (milliamp hours).  We next go to the V-Link-LXRS power profile (http://files.microstrain.com/V-Link-LXRS-Power-Profile.pdf) and we read that the V-Link-LXRS consumes 12.816 mA when sampling a 350 ohm strain gauge on 1 channel at 128 Hz.  By dividing 650 mAh by 12.816 mA, we find that the battery will last approximately 50 hours before needing recharge.

Yes!

However, new LXRS functions such as synchronized sampling, beaconing, etc. will not be available for your older node.

 

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

With the introduction of our LXRS radio technology, and its accompanying increase in radio strength and signal distance, the channel 25 radio frequency (2.475 GHz) and the channel 26 radio frequency (2.480 GHz) created harmonics on the edge of the Zigbee band that precludes their use.

All wireless products, both older and new, continue to support 14 channels running from channel 11 to channel 24.

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

With the introduction of our LXRS radio technology, and its accompanying increase in radio strength and signal distance, the channel 25 radio frequency (2.475 GHz) and the channel 26 radio frequency (2.480 GHz) created harmonics on the edge of the Zigbee band that precludes their use.

All wireless products, both older and new, continue to support 14 channels running from channel 11 to channel 24.

 

 

 

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

With the introduction of our LXRS radio technology, and its accompanying increase in radio strength and signal distance, the channel 25 radio frequency (2.475 GHz) and the channel 26 radio frequency (2.480 GHz) created harmonics on the edge of the Zigbee band that precludes their use.

All wireless products, both older and new, continue to support 14 channels running from channel 11 to channel 24.

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

If you are mixing new nodes and base stations with older nodes and base stations, please be cognizant of these different channel settings.

The Node Discovery function of Node Commander will help you sort out which nodes are on what channels; Node Discovery is channel independent and allows the base station to communicate with any node, no matter what channel it is on

Sampling methods such as synchronized sampling, low duty cycle, network broadcast, etc. require that all nodes are on the same frequency so you will want to insure that you have adjusted the channels settings of the nodes to suit.

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

If you are mixing new nodes and base stations with older nodes and base stations, please be cognizant of these different channel settings.

The Node Discovery function of Node Commander will help you sort out which nodes are on what channels; Node Discovery is channel independent and allows the base station to communicate with any node, no matter what channel it is on

Sampling methods such as synchronized sampling, low duty cycle, network broadcast, etc. require that all nodes are on the same frequency so you will want to insure that you have adjusted the channels settings of the nodes to suit.

All LORD MicroStrain wireless sensor nodes, wireless base stations, and wireless sensor data aggregators are shipped from the factory with their radio frequency set to channel 15 (2.425 GHz).

This channel setting was established during 2012.

Previously all wireless products were set to channel 25 (2.475 GHz).

If you are mixing new nodes and base stations with older nodes and base stations, please be cognizant of these different channel settings.

The Node Discovery function of Node Commander will help you sort out which nodes are on what channels; Node Discovery is channel independent and allows the base station to communicate with any node, no matter what channel it is on

Sampling methods such as synchronized sampling, low duty cycle, network broadcast, etc. require that all nodes are on the same frequency so you will want to insure that you have adjusted the channels settings of the nodes to suit.

In order to return any LORD MicroStrain® product either for repair or return, you must contact us for a Return Merchandise Authorization number (RMA). If you purchased directly from LORD MicroStrain® in the United States, please contact your Sales or Support Engineer to obtain an RMA.  If you purchased directly from a LORD MicroStrain® distributor, please contact your distributor to obtain an RMA.

If you are located in the United States, LORD MicroStrain® supplies you directly.  If you are in located in another country, LORD MicroStrain® products are available exclusively from LORD MicroStrain® distributors.  Please use this locator to determine your distributor: http://www.microstrain.com/support/international

LORD MicroStrain® Support Engineers are always available to support you in any way we can by phone, email, SKYPE or Live Chat from our home page.  Contact details may be found at: http://www.microstrain.com/support/contact-support

LORD MicroStrain® insures all products shipments to their full value unless the customer specifically states a different method.

Microsoft Excel displays the timestamp contained in the wireless node data files incorrectly.  If you were to open the CSV file with Microsoft Notepad, you will see that the timestamp is shown properly.  In order to get Excel to show the human readable time, follow the below procedure:

  • Highlight all of column A (column with the timestamp)
  • Right click on highlighted region and select Format cells...
  • Select the Number Tab in the window that open and choose Custom from the Category box
  • Scroll to the bottom of the list in the Type box, find this entry: m/d/yyyy h:mm and click it
  • Add to the entry an :ss.000 so it now looks like this: m/d/yyyy h:mm:ss.000
  • Click OK

The timestamp will now be correct.

Changing a radio channel on your wireless node and wireless base station is accomplished through Node Commander software.  Follow the four step process outlined below to update your radio channel (frequency) setting.  Note that radio channels on both your wireless node and wireless base station must match to establish network communication.

To change node/base station radio channel:

  1. Right-click Base Station/Node.
  2. Click Configure. 
  3. Click Frequency.
  4. Click Channel, e.g. 24 (2.470 GHz).

The wireless node's effective download rate is ~9.2 kBps, or 73.6 kbps.  In perfect wireless conditions, a node's full 2MB memory can be downloaded in approximately 3.7 minutes.  While 250 kbps is the radio transmission rate, there are others variables that factor into the effective download rate including memory read time, packet overhead, radio acknowledgments, and base station to PC communication.   

Yes, as a courtesy, LORD MicroStrain® will provide an appropriate drill bit and tap to match the DVRT's thread size at a nominal charge.

All software provided by MicroStrain saves data files in CSV (comma separated value) format.  The CSV file is readily importable into any third party analysis program.

The wireless nodes, including circuit boards, antenna, internal battery and enclosure, can withstand shock loads up to 500g. LORD MicroStrain® can provide customization of the nodes by using high-G crystals, potting and non-masted antennas to withstand greater shock loads.

The wireless nodes all have 2 Mbytes of datalogging memory.  This 2 Mbytes is organized into 8,191 ‘pages’ of memory, each page holds 132 data points.  The maximum number of data points that can be held in memory can be calculated as follows: 8,191 pages x 132 data points/page = 1,081,212 total data points.

Now the question arises, ‘how long can a node datalog before its memory is full?’. The answer is that it varies depending on how many channels are being sampled and what sampling rate has been set. Here are two examples:

Let’s set a V-Link-LXRS so that channel 1 is active with a datalogging sampling rate of 2048 samples per second and we launch continuous datalogging.  Our calculation would be:

  • 1 channel x 2,048 samples per second = 2,048 data points per second
  • 1,081,212 data points / 2,048 data points per second = 527 seconds
  • 527 seconds / 60 seconds per minute = ~9 minutes to fill the memory

Let’s set a G-Link-LXRS so that channels 1, 2 and 3 are active with a datalogging sampling rate of 32 samples per second and we launch continuous datalogging.  Our calculation would be:

  • 3 channels x 32 samples per second = 96 data points per second
  • 1,081,212 data points / 96 data points per second = 11,262 seconds
  • 11,262 seconds / 60 seconds per minute = ~187 minutes to fill the memory

The nodes contain an internal high capacity rechargeable battery.  The nodes are provided with an external power supply which is used to recharge these batteries.  The battery life of the internal battery is fully dependent on the data acquisition mode.  High speed streaming will consume the battery in hours while low duty cycling can operate months and months if a low sample rate is set.  The nodes may also be powered externally by an external battery or power supply.

The gateways (base stations and WSDA-1000) and the wireless nodes employ radios with these general specifications (see the individual product data sheet for any variations):

Radio frequency (RF) transceiver carrier 2.4 GHz direct sequence spread spectrum, license free worldwide (2.405 to 2.480 GHz) – 16 channels, radiated power programmable from 0 dBm (1 mW) to 16 dBm (39 mW); European models limited to 10 dBm (10 mW)
RF data packet standard IEEE 802.15.4, open communication architecture
RF data downloading 8 minutes to download full memory
Range for bi-directional RF link programmable communication range from 70 meters to 2 kilometers

 

 

 

 

In FINITE sampling, the user sets a total number of samples to be taken which equates to a time period.  Because the sampling rate per second is known, the user can adjust the number of samples to be taken to determine how long the sampling period will be.

In CONTINUOUS sampling, the user does not set the total number of samples and therefore does not set the time of the sampling period.  By selecting CONTINUOUS sampling, the user is instructing the system to sample data until the user manually stops the sampling (via software), the power is cycled, the on-board datalogging memory is full, the battery dies, the power fails, etc.

LORD MicroStrain® Wireless Sensor Networks provide several data acquisition modes including:

  • Synchronized Sampling
  • Armed Datalogging
  • Streaming
  • Duty Cycle

See the particular wireless node for specifics.

 

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