Lord MicroStrain V-Link-LXRS Instruction Manual

1
LORD TECHNICAL NOTE
V-Link®-LXRS®and SG-Link®-LXRS®
Using Pressure Transducers
Overview
The LORD MicroStrain® V-Link®-LXRS®Wireless 7 Channel Analog Input Sensor Node will support pressure
transducers on channels 1, 2, 3 and 4 and the SG-Link®-LXRS®Wireless 2 Channel Analog Input Sensor Node will
support pressure transducers on channel 1. This technical note explains use of a typical pressure transducer with SG-
Link®-LXRS® and Node Commander®software; the V-Link®-LXRS® mirrors the instruction.
Pressure Transducer
For our example, we are using a Viatran Model 817 pressure transducer. The Model 817 is a submersible instrument
designed to give accurate level measurement in up to 1,200 feet of water, and is used for both general water
applications and corrosive applications.
Wiring
Refer to the Model 817 Installation Data Manual (page 4) and the SG-Link®-LXRS®Quick
Start Guide (frame 2C) to connect the sensor to the node.
Model 817 Pressure Transducer
SG-Link-LXRS
Lead color
Lead use
Pin number
Pin nomenclature
Red
+ Power
1
VXC
Black
+ Signal
2
S+
Green
- Power
4
GND
White
- Signal
3
S-
Shield
GND
4
GND
Table 1: Wiring
Step 1
Locate the specific calibration sheet provided by the pressure transducer
manufacturer and any other documents as necessary to determine the
following parameters:
oCalibration Voltage
oFull Scale Reading
oMeasurement Range
We find the Calibration Voltage embossed on the barrel of the
transducer (10 V).
We find the Full Scale Reading (86.073 mV) on the calibration
document, as shown in Figure 2.
We find the Measurement Range embossed on the barrel of the
transducer (20 feet).
Figure 1: Model 817
Pressure Transducers
Figure 2: Calibration Document

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V-Link®-LXRS®and SG-Link®-LXRS®Using Pressure Transducers
Step 2
Download our Pressure Transducer Calculator here. It is a Microsoft Excel spreadsheet (.xlsx).
Open the spreadsheet and enter values in the green boxes as follows:
oEnter 10 in the green Calibration Voltage cell of the spreadsheet.
oEnter 86.073 in the green Full Scale Reading cell of the spreadsheet.
oEnter 240 in the green Rated Depth cell of the spreadsheet. We are electing to make our engineering
units (EU) in inches instead of feet, i.e., 20 feet * 12 inches =240 inches as our Measurement Range.
oEnter 104 in the green User Settable Gain cell of the spreadsheet. 104 is the default Hardware Gain of
the SG-Link®-LXRS®.
Following our inputs, we see a result of ~201 generated as our Max Node Output using the Low-scale Balance.
This 201 is 201 inches; our setup, as we have done it, allows us to measure water depths of 0 to 201 inches.
Note: by varying the User Settable Gain and the Balance (high, mid, low), we would be able to make setups
with higher and lower resolution, and differing ranges. Please speak with your LORD MicroStrain®support
engineer if further detail is needed.
Figure 3: Pressure Transducer Calculator
Step 3
Establish communication as normal between the SG-Link®-LXRS® and Node Commander®software.
Right-click the node and a drop-down menu will appear.
Click Configure.
Click Configure Node and the Configuration screen will appear.
Click the Channels tab.
Enable channel 1 only by clicking the checkbox; disable channels 2, 3 and 4.
Click the Configure button (…) to the right of channel 1 and the Channel 1 Configuration screen will appear.
Select 104 (default) in the Hardware Gain drop-down.
Select the Low auto-balance radio button.
Click the Auto-Balance button and an Information window will appear indicating Channel 1 has been balanced
to ~2048 bits.
Click OK and the Information window will disappear.
Select Custom Units in the Class drop-down.

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V-Link®-LXRS®and SG-Link®-LXRS®Using Pressure Transducers
Select Other in the Units drop-down; Other
will now represent ‘inches’.
Click the Modify button.
Enter 0.06546 in the Slope textbox; this
value is pulled from the orange Slope cell,
calculated in our spreadsheet.
Enter a temporary value of 0 in the Offset
textbox; we will change this shortly.
Click the Lock button.
Click OK and the Channel 1 Configuration
screen will disappear.
Click the Streaming tab.
Uncheck the Continuous Streaming
checkbox.
Enter 20000 in the Sweeps numberbox
(~27 seconds).
Click Apply.
Click OK and the Configuration screen will
disappear.
Step 4
Right-click the node and a drop-down menu will appear.
Click Sample.
Click Stream.
Click Start and channel 1 will plot left to right as a green plot line.
When the stream is ended, observe the mean value of the plot line. In our example in Figure 5, we see a mean
value of 132.95.
Figure 5: Streaming Graph
Right-click the node and a drop-down menu will appear.
Click Configure.
Click Configure Node and the Configuration screen will appear.
Click the Channels tab.
Click the Configure button (…) to the right of channel 1 and the Channel 1 Configuration screen will appear.
Click the Modify button.
Enter a value of -132.95 into the Offset textbox; we add the minus to subtract the offset of 132.95 and zero the
output.
Figure 4: Channel 1 Configuration Screen

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V-Link®-LXRS®and SG-Link®-LXRS®Using Pressure Transducers
Click the Lock button.
Click OK and the Channel 1 Configuration screen disappears.
Click OK and the Configuration screen disappears.
Again, right-click the node and a drop-down menu will appear.
Click Sample.
Click Stream.
Click Start and channel 1 will plot left to right as a green plot line.
Observe that channel 1 is now streaming at about 0 (zero).
Note: As a result of our configuration, the engineering units on the Y-axis are in ‘inches’; that is to say ‘inches of
depth’. The pressure transducer will be measuring 0 inches of depth as it sits on your bench as you perform
this setup.
The system is now configured and ready for use.
Support
LORD MicroStrain®support engineers are always available to expand on this subject and support you in any way we
can.
Copyright © 2013 LORD Corporation
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MicroStrain®, and Little Sensors, Big Ideas® are trademarks of LORD Corporation.
8401-0028 rev 000
LORD Corporation
MicroStrain®Sensing Systems
459 Hurricane Lane,
Unit 102
Williston, VT 05495 USA
www.microstrain.com
ph: 800-449-3878
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