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The EH-Link™ is a versatile multi-sensor node that runs on ambient energy sources such as vibration, light, and inductance. 

Product Highlights

  • Sophisticated self-powered node can harvest energy from ambient energy sources for indefinite remote deployment.
  • On-board high-speed triaxial accelerometer, internal temperature sensor, internal relative humidity sensor, and an analog input channel provide many sensing options.
  • Supports auxiliary energy storage options such as super-capacitors and rechargeable thin film batteries

LORD MicroStrain® LXRS® Wireless Sensor Networks enable simultaneous, high- speed sensing and data aggregation from scalable sensor networks. Our wireless sensing systems are ideal for sensor monitoring, data acquisition, performance analysis, and sensing response applications.

The gateways are the heart of the LORD MicroStrain wireless sensing system. They coordinate and maintain wireless transmissions across a network of distributed wireless sensor nodes . The LORD MicroStrain LXRS wireless communication protocol between LXRS nodes and gateways enable high- speed sampling, ±32 microseconds node- to- node synchronization, transmission range up to 2 kilometers, and lossless data throughput under most operating conditions.
Users can easily program nodes for data logging, continuous, event- triggered, and periodic burst sampling with the Node Commander ® software. The web- based SensorCloud™ interface optimizes data aggregation, analysis, presentation, and alerts for gigabytes of sensor data from remote networks.

 

Datasheet Manual
Large Quantity & OEM Orders

Wireless Simplicity, Hardwired Reliability™

High Performance

  • Potential power sources include: solar energy (photovoltaic); electromagnetic fields (electrodynamic); thermal energy from temperature changes (thermoelectric); strain and vibration (piezoelectric); high impact energy, and capacitive discharge.
  • Solar energy harvesting input operates in low light levels.
  • Thermal energy harvesting input operates in thermal gradients below 8 ˚C when used with Peltier Thermoelectric Generators (TEGs).
  • User-programmable sample rates up to 512 Hz

Ease of Use

  • Scalable, wireless sensor networks up to 70 m
  • Easy out-of-the-box wireless sensing for most analog sensors

General

Sensor input channels

Energy harvesting, 3 source types and channels

Differential analog, 1 channel

Integrated sensors

Triaxial MEMS accelerometer, 3 channels

Internal temperature, 1 channel

Relative humidity, 1 channel

Energy Harvesting Inputs

Wide range voltage (WRV) input

5 to 20 V ac/dc peak, (piezoelectric, electrodynamic, photovoltaic, electromagnetic)

Capacitive discharge voltage

(CDV) input

20 to 130 V ac (pulsed piezoelectric)

Ultra-low voltage (ULV) input

20 to 600 mV dc (thermoelectric, Peltier, thermopile)

Analog Input Channel

Measurement range

Differential: full-bridge, 350 Ω (factory configurable), user programmable gain and offset

Accuracy and resolution

± 0.1% full scale typical, 12 bit resolution

Bridge excitation voltage

+2.7 V dc, 50 mA

(pulsed @ sample rates 16 Hz to conserve power)

Integrated Accelerometer Channels

Measurement range

± 16 g

Accuracy and resolution

± 4 mg, 12 bit resolution

Integrated Temperature Channel

Measurement range

-40 °C to 85 °C

Accuracy and resolution

± 2 °C (at 25 °C) typical , 12 bit resolution

Integrated Relative Humidity (RH) Channel

Measurement range

0 to 100 %

Accuracy

± 2 % (10 to 90 % RH), ± 4 % ( 0 to 10% RH and 90 to 100% RH)

Repeatability

± 0.1 %

Sampling

Sampling modes

Low duty cycle

Sampling rates

Continuous sampling: 1 Hz to 512 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.

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 0 dBm

RF communication protocol

IEEE 802.15.4

Range for bi-directional RF link

70 m line of sight

Energy use

Startup: 12 μJ; sampling: accelerometer or RH sensor only, 105 μJ/sample; sampling: differential input only, 168 μJ/sample; data transmission: 92.4 μJ/packet

Operating temperature

-20 ˚C to + 60 ˚C

Operating humidity

0 to 95 %, non-condensing

Acceleration limit

500 g standard

Physical Specifications

Dimensions

88 mm x 39 mm x 16 mm

Weight

26 grams

Integration

Compatible gateways

All WSDA® base stations and gateways

Compatible sensors

Bridge type analog sensors (for analog inputs)

Connectors

Screw terminal blocks

Software

SensorCloud™, Node Commander®, WSDA® Data

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

Software development kit (SDK)

Data communications protocol available with EEPROM maps and sample code (OS and computing platform independent) http://www.microstrain.com/software-development-kits-sdks

Regulatory compliance

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 most common cause of this issue is that the customer connects the WSDA directly to the PC via the ethernet cable without setting the WSDA -1000 up for Static IP first.  If you refer to page 3 of the quick start guide http://files.microstrain.com/WSDA-1500_QSG_(8501-0057).pdf

To connect to the gateway Control Panel through Live Connect™ an initial connection to a DHCP enabled network is required.

1. Connect the host computer and gateway to the DHCP network, and apply power to the gateway.

Verify the gateway status indicator shows that it is on and has completed the boot up process.

 

This means that the WSDA and the computer needs to be connected to a device (like a router) that will assign an IP address to it.  Once this is done the user will be able to log into the WSDA web control panel (using the router assigned IP), and change the network mode to Static IP in the configuration screen.  They would then need to change the network card of the computer to a complementing Static IP.  After this is done the user should be able directly connect the WSDA to a computer.

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

To enable customers to try our standard products risk free, LORD MicroStrain® offers a 30 day return on the purchase of a starter kit. In order to take advantage of this offer, a purchase order or payment for the starter kit is required when the order is placed. 30 day trial details may be found at: http://www.microstrain.com/support/warranty

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.

LORD MicroStrain® warrants its standard products to be free from defective material and workmanship for a period of one (1) year from the original date of purchase.  Warranty details may be found at: http://www.microstrain.com/support/warranty

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.

Yes.  The EH-Link is shipped with Node Commander software which enables immediate out-of-the-box operations with the host computer.

 

Yes.  The EH-Link has an on-board radio which operates in the 2.4 GHz direct sequence spread spectrum and is license-free worldwide.  The radio has a radiated power of 0 dBm (1 mW) and a range of 70 meters line-of-sight.  The EH-Link communicates with a base station that is connected to the host computer.

The EH-Link has the following on-board sensors:

  • triaxial accelerometer
  • relative humidity and temperature sensor
  • external single channel differential (Wheatstone bridge) input

The EH-Link Pioneer Kit, LORD MicroStrain® part number 6320-0041 includes 1 EH-Link wireless sensor node, 1 solar demo harvester and 1 TEG demo harvester, enabling users to set up an Energy Harvesting demo in minutes.

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 input impedance is dependent on the programmed sample rate, the transmit rate, and how many and what type of sensors are enabled. As can be seen from the product datasheet, there are 3 different harvester/generator inputs, and a myriad of programmable operating modes to accommodate varied harvesters and energy environments.

The most commonly used harvester input is the Piezo input, an ultra-efficient switchmode converter. Figure 1 below clearly demonstrates the capability of the EH-Link versus different wireless transmit rates. Figure 1 shows test results where the applied voltage was 7.5V, a 1000 ohm Wheatstone bridge is being measured, and the transmit rate and packet payload size were varied. In this test the sample rate is fixed at one sample per second. The number of measurements saved up for transmission was varied from 1 to 30, where at 1 a single measurement was transmitted over the wireless link once per second. At 30 in this test, 30 measurements are accumulated and transmitted every 30 seconds. This is done to demonstrate that much less power is used to sample than to transmit. It is important to note that even at 30, the data sample timing is preserved and no data are missed in the received measurement stream.

Another harvester input, the 'ultra low voltage' input, is very low impedance and is intended for thermoelectric generators and thermopiles, which have very low voltage and relatively high output current. The input impedance on this input is on the order of 6 ohms, and varies a little with operating mode. With our demo TEG harvester is able to sustain continuous sampling at 64 samples per second and one transmission per second with a temperature differential of only 8 degrees Celsius between the mounting surface and the heat sink on the cool side.

The third input is an ultra high impedance AC type intended for use with high voltage piezo materials where the capacitance of the piezo is discharged at a threshold of approximately 130V peak. This is done to maximize the 'V' term in the capacitive energy equation (one half C*V squared). This input is somewhat experimental but has been shown to be very high efficiency and very high (>1 megohm) input impedance before the discharge threshold is reached, making it ideal for use with high voltage piezo ceramics.

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 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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