Wisen innovation WISENMESHNET L-Series VW Interface Node User Manual

WISENMESHNET® L-Series VW Interface
Node
User Manual
Wuxi Wisen Innovation Co., Ltd.
November 2019

Revision History and Clarification

Document Definition:

It defines the specifications (i.e., introduction, technical features, deployment, and maintenance methods) of the WISENMESHNET® VW interface node, which is one of the key components in WISENMESHNET® Low Power, Intelligent, Wireless Sensor Network (WSN) system. It is responsible to:

• Sample data from external Vibrating Wire sensors, such as strain gauges, displacement transducers, piezometer, settlement sensors, pressure cells, load cells, etc.;
• Form a time-synchronized Wireless Sensor Network with other nodes in the system;
• Transmit the data packet to a gateway.

Scope：
Customer Site Project Managers and Engineers, Wisen Service Engineers, etc.

Product Introduction

The WISENMESHNET ® Vibrating Wire (VW) Interface Node is one of the key products in our patented WISENMESHNET ® geotechnical safety monitoring system. Working together with the WISENMESHNET ® gateway product and our customer’s VW-type sensors, it intelligently delivers the real-time VW-derived deformation of the structure to the information center. The WISENMESHNET ® VW Interface Node operates using our core technology, i.e., the WISENMESHNET ® Low Power, Intelligent, Wireless Sensor Network protocol, together with its internal high precision frequency sampling module and power unit. This interface node is compatible with conventional geotechnical vibrating wire- type sensors measuring in the range from 400 to 6000Hz. This product satisfies the three fundamental identities of the system:

A. Network Life Span: to maximise battery life across the mesh network as a whole;
B. Network Data Arrival Rate: to minimise data packet loss;
C. Single Node Environmental Coverage: to maximise radio coverage.
Our product has IP66 and is designed to work in a tough environment. It is small in size, reliable in performance, easy for maintenance, has high precision during sampling, and has a strong immunity to radio interference.

WISENMESHNET® VW interface node is Compatible with all different brands & types of high-quality Vibrating Wire sensors, therefore it can be applied in all different related monitoring projects. Examples of VW sensors: Strain Gauges; Displacement Transducers; Piezometers; Settlement Sensors; Pressure Cells; Load Cells.

System Structure Layout

Node & Radio Features

Node Features:

Basics

Battery Power| Qty. x 1 (3.6V Lithium primary D-Cell ER34615)
Accuracy Stop Voltage| 2.1VDC
Mesh Stop Voltage| 2.1VDC
Battery Connection| Standard Aluminium Battery Holder
Working Current (DC)| Max. 60mA (Typ. 48mA)
Local Storage| Min. 450 Messages during Meshing
L x W x H| 100 x 100 x 60mm
Weight| 0.60kg
Cable Gland| Qty. 1 x EMC-CMA12 for external VW sensor connection
Wire Connection| Spring-type wiring terminal
Externally Connected VW Sensor
Sensor Type| Vibrating Wire Typed
No. of Inputs| 1 Channel
** Sensor Connection| VW Type of 5 wires: VW+, VW-, T+, T-, GND. Note: Temperature wires (or a 3kΩ resistor) must be connected to the T+ & T- terminals so VW node can work properly; Ground wire between a node and a sensor must be connected.
Parameter| Resonant Frequency (Hz)
Range| 400 to 6000Hz
Accuracy| 0.015% at Any Reading
Sensitivity| 0.002Hz@400Hz or 0.05Hz@6000Hz
Cable Length| <= 1.1km
External Thermistor Sensor
Parameter| Thermistor Resistor of 3kΩ @25°C
Range| 0.052kΩ to 113.096 kΩ
Accuracy| 0.12kΩ or 2°C
Standard System Parameter
Temperature| Range: -40 to 85°C, Accuracy: +/-1°C, typical 0.5°C; Resolution: 0.1°C
---|---
Voltage| Accuracy: +/-0.1V
WSN Interface
WSN Protocol| WISENMESHNET® Protocol
Re-Calibration Method
Inspection Period| Every 3 Years by Manufacturer (or inspected by arranged methods)
Industrial Standard**
Casing and Painting Materials| Aluminium-Alloy Die Castings 12 (Epoxy Polyester Powder Coating)
IP Rating| >= IP66
Operating Temperature| -40 to 85°C

Radio Features:

| FCC 915MHz System| CE 868MHz System
---|---|---
Radio Band| 902-928MHz| 865-868MHz
Central Frequency ( Default )| 905 /910/915/920/925MHz| 865.75 /866.25/866.75/867.25MHz
Default Transmit Power| 18dBm| 14dBm
Receive Sensitivity| -112dBm
Bandwidth| 500kHz
Transmission Speed| 19.2kb/s
No. of Mesh Hop*
Supported| ****

6 Hops

Sampling Interval| 1-60mins

Antenna Description

| Mesh Antenna| Omni-directional (20cm in length) or Customised
2/3/4G-Antenna| Omni-directional 3.5dBi (20cm in length) or Customised
Antenna Connector| SMA (M)

• E.g., the radio link from a gateway to the 1s player node is called the 1st hop.

Terminologies

Operation Procedures

5.1．System Deployment Notifications

1. Location: The deployment location of a VW Interface Node is usually determined by the required monitoring or inspection location;

2. Before any VW Interface Node is switched on, two tasks will need to be carried out:
   A. Unlike the Tilt Node which has a MEMS tilt sensor embedded in the node, the VW sensors chosen by the customer, e.g., VW crackmeter, VW settlement gauge, VW strain gauge, etc, must be connected to the VW
   Interface Node;
   B. A gateway must be deployed, powered on, and proven to be working properly. Otherwise, the nodes will need to be switched off, then switched on again after a gateway is switched on. So simply speaking, the rules to follow to correctly deploy a WISENMESHNET system are:
   Gateway first, then nearby nodes, then further nodes.
   

3. During deployment, the Serial Number, i.e., SN of a node and the orientation of the VW sensors deployed against their site references must be recorded;

4. The connections between a customer-chosen VW sensor and a Wisen VW Interface Node must strictly follow the rules stated in this document;

5. All the nodes should have their antenna point upwards.

5.2．Choosing your VW Sensors

Most problems encountered during monitoring are caused by the cabling and the connections of VW sensors, especially when the environment is experiencing strong Electromagnetic (EM) interference, such as power tunnels. The essential requirements when choosing a VW sensor are listed below:

1. The sensor cable: insulation sleeve, braid screen, 4 coils, one drain wire, where:
   A. The braid screen is connected to the box;
   B. The 4 coils are connected to the unit signal terminals;
   C. The 1 drain wire is connected to the electrical circuit ground.

2. Reputable manufacturers.
   (Notice ****: Wisen can always recommend an updated EMC solution and some suitable manufacturers around the world to our customers. Please contact Wisen for further information).

5.3．Deployment Procedures

1. Open the box: Take the node out of the package and open its lid;

2. Insert Battery: By default, a node does not contain a D-Cell battery. Therefore the battery needs to be inserted.
   Notice **** : +ve and –ve orientation must be correct, otherwise, the internal circuit may be damaged; As our VW
   Interface Nodes has more than one battery installed, special attention must be paid to avoid shorting the battery by the battery holder.

3. Antenna Installation: Screw the antenna tightly onto the node;

4. Sensor Installation: To ensure a customer-chosen VW sensor is deployed onto a structure correctly, please strictly follow the corresponding manufacturer sensor instructions. Once a VW sensor is deployed and pre-tensioned, please use a handheld readout device to confirm valid readings can be read;

5. Sensor connections to Node:
   A. Strip the cable sleeve back by 8mm.
   B. The 5 wires from the cable are VW+, VW-, Thermistor (Temperature)+, Thermistor (Temperature)-, and Ground. Please refer to the sensor datasheet to identify the purpose of the stripped wires.
   C. Untighten the gland cover, insert cable through the gland, then connect the 5 wires correspondingly as shown in the Figure below.
   D. Once the wires are connected, please tighten the gland cover firmly to ensure its IP rating on that channel.
   
   Notice 1: The cable gland diameter of the 1-VW Interface Node is 8mm.
   Notice 2: All 5 wires must be connected, minimize electrical interference and possible loss of precision.
   Notice **** 3: Within any electrically noisy environment, nodes with sensors must be >= 0.3m away from the source of the noise.

6. Power On: Once all the VW sensors are connected, turn the switch on. Now you should be able to see 3 LEDs flashing 3 times, which means the node is on properly. Then switch off the node to save power if the gateway is off;

7. Tighten the 4 Cap-Hex-Head screws of the lid to secure the enclosure IP rating;

8.  To validate the sensor data, please visit WISENMESHNET® Visualisation Platform for further details.

5.4．Mounting Options

VW Interface Node can be deployed with various methods. However, the priciple is to make sure it is firmly attached to the installation surface.

General Maintenance and Notification

1. Once a node is installed in the field, please minimise any man-made disturbance so that data quality can be maintained;
2. Radio communication will be impaired if the antenna is covered by metal or very moist soil material;
3. Due to the discharge characteristics of the recommended battery, a battery replacement should be carried out when a node-reported voltage reaches 2.7V, at which point you have approximately 3 weeks to change the battery;
4. Our product will use all the possible capacity in a battery down to a stop (minimum) voltage, which has been specified in the Features table. When this occurs, our WISENMESHNET® protocol will send you a warning then it will enter a deep sleep mode until a new battery is installed;
5. If the data from nodes are showing unexpected results or are not being sent back to the Wisen gateway, then please carry out the investigation using the following two-stage procedure:
   A. Remote Inspection of historical data, to identify the following:
   a) Whether the heart-beat message has been sent back successfully at each time interval;
   b) Whether the battery voltage is too low, if yes, please change the battery unit;
   c) Whether the signal strength has become significantly weaker than it was previously. If yes, please check the antenna has been screwed on firmly.
   B. On-site Inspection: If all the above are good, please arrange an on-site inspection to check:
   a) Whether a Node has visible external damage;
   b) Check the box lid to see if it is firmly tightened;
   c) Whether the antenna is bent or damaged and that the node is not blocked by new construction, e.g., hoardings;
   d) When it is possible, check that the signal strength is normal by using a spectrum analyser;
   e) Open the lid, to see whether the battery is firmly attached to its holder;
   f) Use a multimeter to measure the battery voltage. If it is below the stop (minimum) voltage, replace the battery.
   g) Make sure the 5 wires are connected properly, if necessary, please disconnect the wires to inspect.

Notices **** :
i. Case One: If any change has been made from the list above, please inspect the data at the remote server;
ii. Case Two: If all the actions from the list above have not cured the problem, please contact Wisen. We will be happy to help.

Package and Accessories

Standard:

Safety and Warning

Warning: Please read the following instructions carefully.
1）Operation Safety

• Before taking any action, please read all the information provided carefully, and keep the guidance documents safe;

• Ensure that any procedures and installations are correctly carried out. The communication cable and the case must be grounded.

• This product has been designed to meet a certain water-proof level. However, it becomes water vulnerable when the lid is open or if the cable gland has not been sealed properly.
  2）Electric Safety

• To install the battery into a holder, please follow the “+” (positive) and “-” (negative) signs in any Wisen product.
  Wrong orientation of a battery could potentially cause unit damage. Notice ****: The orientation of battery can vary among products.

• When disconnecting the battery, please take special care not to apply excessive force, otherwise, the battery holder and the nearby circuitry may be damaged.
  3）Warning

• The battery in the product has a relatively high capacity, so please take special care during storage and usage.

• This product must not be disassembled under any circumstances, to do so will void the warranty and may leave the product in a dangerous state;

• If all of the above are not followed, the manufacturer cannot be held responsible for any damage and injury caused to the users.
  4）Caution

• Danger of explosion if the battery is incorrectly replaced. Replace only with the type recommended by the manufacturer.

• When disposing of the batteries, please contact your local authorities or dealer and ask for the correct method of disposal.

Contact

– Wuxi Wisen Innovation Co., Ltd.: www.wisencn.com
– Email: marketing@wisencn.com

www.wisencn.com
Wisen Innovation Technical Doc. No.2019
WISENMESHNET® L-Series VW Interface Node – User Manual

References

• Wisen Innovation Ltd-悟莘科技有限公司
• Wisen Innovation Ltd-悟莘科技有限公司

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