Device Names

A data logger (or datalogger) is a device that retrieves data from sensors and stores it for later retrieval. While the word “datalogger,” and its variants (“logger,” “data recorder,” “programmable data logger”), are common in the environmental monitoring industry, other industries sometimes use slightly different terminology.

For laboratory settings, a “data acquisition system” (DAQ or DAS) is a common description. These are typically bench-top instruments and may be focused on high frequency, or specialized data measurements. The connectors, enclosure, and operating temperature are intended for indoor applications.

In the industrial sector, “data recorder” or “process recorder” might be used to monitor ongoing automation system activities. The data recorder in conjunction with the software has been given the verbose description of “operational historian”. Regardless of the differences in terminology, the basic idea is to measure and store data from sensors.

Common Data Logger Features

Data logger features can vary substantially, with different designs for specific applications and cost constraints. However, a general purpose data logger typically has some features that go beyond simply measuring and storing data. These features include:

• Structured data storage (example: CSV)
• Broad sensor electrical and protocol compatibility (analog, digital, pulse, frequency)
• Scheduled and programmable measurements
• Basic processing of raw data, such as average, min, max

Data Storage

Data storage can be as simple as the raw numbers in a text file, but generally there is structure such as an associated time stamp. These may be stored as columns in a CSV file. Storage of metadata (equipment used, units, and so forth) is also important to record.

Sensor Compatibility

It is difficult for manufacturers to design a device that is compatible with every possible sensor, but general purpose data loggers support a broad range of digital and analog sensor outputs.

Data loggers may be limited by the number of ports on a device, program inflexibility, and incompatibility with sensor output type. This means that data logger hardware must be evaluated in conjunction with the sensors required for a particular application.

Programmability

Sensor measurements typically occur on a schedule that ranges from milliseconds to hours, depending on the application. Programmable data loggers allow for adjusting measurement schedule. Often calculated values, such as minimum, maximum, and average can be stored.

Advanced Data Logger Features

More sophisticated general purpose data loggers have a number of advanced features:

• Concurrent sensor measurement timing
• Advanced programmability
• Data quality monitoring
• Sensor equipment controls
• Data transmission
• Field Serviceability

Measurement Timing

Timing of measurements is often crucial for data interpretation and advanced data logger software is structured to execute measurements concurrently rather than sequentially. For example, if two sensors are connected to the data logger and one of the sensors requires 10 seconds to perform a measurement while the other sensor only requires 1 second, the faster measurement should not wait for the slower measurement to finish. Concurrent execution enables both measurements to stay on schedule.

Timing can also be important for the operation of secondary sensor equipment like wipers on optical sensors and sensor heaters. Advanced data loggers can control secondary equipment and be programmed to activate it on a schedule or in response to events.

Advanced Programmability

Data loggers have a wide variety of user interfaces. Many programmable data loggers use a proprietary script language or configuration wizard. Proprietary software tools will facilitate configuration, data collection, and data visualization, but may limit program flexibility. Whereas a data logger built from a small micro-controller device like Arduino may have more flexibility, but will require high-level programming skills to configure and collect data.

Data Quality Monitoring

Advanced programmability allows users to perform data quality monitoring at the point of measurement. The data logger can then react to sensor readings by initiating a new measurement, resetting a device, or sending alerts to operators.

Control Output

Some data loggers also include control outputs, allowing them act on measurement conditions, such as turning off a pump when water level reaches a set point.

Data Transmission

Historically, getting the data off of the data logger has required a manual task involving connecting the device to a computer and transferring files using proprietary software. Modern data loggers use automatic data transmission via the internet, cell phone, satellite, or radio. Data transmission enables live monitoring of the data collection and automatic data monitoring helps ensure the data is immediately useful. Real-time transmissions ensure that operational problems can be rapidly identified and addressed.

Field Serviceability

Field serviceability is critical for environmental data loggers. They are often deployed in remote locations. Any features that limit the equipment required for service or facilitate troubleshooting will result in time and cost savings to the user, as well as improve up-time.

An LCD or OLED display can allow for better on-site system monitoring and troubleshooting.

In addition, a user input method is a necessary companion to the display. Even paging through current measurements or error codes can be an invaluable aid to field service technicians.

Animal damage, weather damage, and normal wear and tear will damage cables. Field serviceable connectors can be important for unexpected repairs.

Overall, system design that minimizes tools, cables, software, and equipment required for field activities is an important design priority.

Dyacon MDL-700

This spring, Dyacon is introducing the MDL-700, a fully featured data logger that is modular in design to accommodate a wide range of applications. One unique feature of the MDL is the Linux operating system. Rather than using proprietary software that offers a limited number of features, the MDL can be programmed however the user desires. It is compatible with languages like C and Python out of the box.

We also provide open-source Python based software (pyMDL – https://github.com/dyacon/pyMDL) with the goal of implementing as much of the functionality discussed above as possible. PyMDL is still in early development stages, but should be usable by almost anyone by the time the MDL begins shipping to customers in March.

Since the software is open source, people are welcome to contribute new features or to take the code and customize it to their unique needs.

Summary

No tool is right for every job. Data loggers come in unique flavors for each application.

Please contact Dyacon if you have any data logger questions. We are happy to help if we can or refer you to another source if we can’t.

Tech Fascination

When a new technology comes out, it tends to get over-used. Often it is used where it makes a splash, but is impractical.

Blue LEDs for example. The light is a high-energy wavelength. When used on visual displays, such as in your car instrument panel, they can appear brighter than a red or yellow. Consequently, it may be difficult to tell whether the button your are pressing is defrost or A/C. And, speaking of cars, who likes the bright, blue HID head lights??

UAVs are another case in point. As a single-function toy, the shine often wears off before they crash. But, for an industrial user, UAVs can play a valuable role. The practical applications are still unfolding.

Ultrasonic Anemometers

The allure of new technology can be practical as well as trendy. Ultrasonic anemometers offer the potential to resolve vulnerabilities of mechanical anemometers; marketing information often promotes the lack of moving parts.

The notion of a static instrument determining wind speed and direction is rather intriguing. But in a professional environment, fascination for the latest tech must also be tempered with practicality.

Ultrasonic wind sensors are now available across the price spectrum, from a few hundred dollars to several thousand. Like most things, you get what you pay for. Measuring the time-to-travel of a sound pulse is really rather rudimentary; electronics do timing very well. Most products work well on the bench or in “typical” conditions. It is reliability over the board range of conditions that exposes the weak from the strong, the good from the bad, and (generally) the cheap from the expensive.

In addition to the advantage of no moving parts, ultrasonic anemometers can be very compact. The small size can also make them easy to heat.

Since there is no mechanical inertia, ultrasonic anemometers can measure very low wind speeds. But, this does not mean that wind measurements are instantaneous, nor accurate. Conventional ultrasonics can experience spurious measurements at low wind speeds.

Due to the turbulent nature of air, sonic anemometers must take multiple measurements in order to provide a wind speed value. Multiple measurements are also necessary to eliminating noise, spurious measurements, and effects of transducer contamination. The number of sound pulses and numerical processing of these measurements will affect the final value produced.

In some sensors, the number of samples used for measurements is configurable. A 1 Hz rate (once per second) sample frequency is typical. Depending on the sampling and filtering, the resulting value may act similar to mechanical momentum.

Snow, rime, and rain are vulnerabilities of all wind measurement devices. For unheated sensors, the vulnerability isn’t much different and will be affected more by the mechanical design than the measurement technology.

Ultrasonic transducers are affected by rain. That is why most designs have the transducers mounted on a top “hat,” facing downward. Nevertheless, splashing of wind-blown rain inside of the measurement cavity may cause some disruption of the transducer and measurements.

Insects often like dark, protected spaces. Spiders like to suspend their webs between structural gaps. Depending on the insect environment, ultrasonic sensors can create inviting compartments. Bird contamination can also disrupt ultrasonics. The meteorological department of my state department of transportation abandoned ultrasonic anemometers for their highway monitoring due to these vulnerabilities.

While the technology itself may be “maintenance-free,” it does not mean that the equipment does not need to be serviced.

Finally, ultrasonic anemometers are typically expensive.

3-Cup Anemometer

In selecting the right tool for the job, “old” technology shouldn’t be eliminated from consideration.

While many ultrasonic anemometers claim to be “low-power,” they are no where close to mechanical anemometers. For example Dyacon WSD-1 with digital output only draws about 2 mA.  As a comparison, I am not aware of a sonic that is lower than 17 mA. Most that I have seen are in the 30 mA to 60 mA range.

In the power budget, one also has to consider the device that is reading the sensor. So, the anemometer is only part of the equation.

A fully operational Dyacon weather station with cell phone draws less than 30 mA average.

Why is power usage important? Because it impacts the cost of the full system and ongoing maintenance. More power means, larger battery, larger enclosure, larger solar panel, larger brackets, larger shipping boxes, higher shipping cost, and higher maintenance cost.

Birds and bugs typically have no effect on Dyacon wind sensors. A bird may perch on the top for a while, but, due to its slender design, it typically can’t be fouled by what they leave behind. The moving components and small gaps are not susceptible to insect fouling.

Ah, but, what about the wear components?

Unlike most wind vanes, Dyacon uses a magnetic sensor. The anemometer itself uses a reed switch. Both are non-contact elements. Yes, the bearings can become contaminated. A service interval of 3 to 5 years is recommended, depending on the environment. Until that time, all you have to do is visually ensure that the components are moving. This makes for intuitive troubleshooting.

Dyacon wind sensors are mechanically robust. Our sensors have survived a number of falls and bird impact. The cups are replaceable in the field. The aluminum mechanism ensures reparability, protecting the user’s investment.

Summary

Two main points:

1. Select the right tool for the job. Both of the above technologies have their place.
2. The wind sensor is only one piece of the system.

We strive to provide professional equipment for the commercial and industrial environment. Not only is our equipment robust, with good connectivity options, it is generally easy to use. This allows users to install, configure, and maintain the equipment, minimizing both down time and total cost of ownership.

Please drop us a note.

Eugene

Back Up (beep, beep, beep …)

For those of us that have been around the block a few times, it seems like the same (or slightly evolved) technology picks up new names every few years. An observer might think that there must be a Global Market Stimulation bureau somewhere dedicated to reinvigorating technology that they think should be adopted. (Or, maybe marketing people think we won’t noticed that they just changed the name on the same stuff.)

Dyacon began when the rugged, on-board computer products division was separated from the parent company. At the time (2007), the concept of automated data communications from a fixed or mobile asset was called telematics. This was intended to be a little more board than “telemetry,” which would typically just mean the transmission of measurement data.

Later, this evolved into machine-to-machine communication. That name was too long, so it was shortened to M2M, which sounds more trendy.

That still didn’t seem to capture the imagination of society, so Internet of Things was invented. Again, the name was too long, so it was initialized to IoT. Yet, my toaster is still dumb (which I prefer) and my car still has a cassette player (which I don’t prefer since it ate my Simon and Garfunkel Greatest Hits tape–now all it plays is silence). (If you didn’t get the “silence” reference, you probably haven’t heard “telematics” either.)

On-Board Vehicle Computers

Like general telemetry technology, mobile asset telematics has included a similar range of names and applications over the years including: AVL (automatic vehicle location), EOBR (electronic onboard recorder), and ELD (electronic log device).

Dyacon continues to design and manufacture open-programmable computer products for the vehicle telematics market. These products are now branded under ControlTrac.

CT650 is our latest on-board computer. Unlike off-the-shelf industrial computers, CT650 is purpose-built for the vehicle market. It utilizes automotive connectors, is sealed, and compact. The I/O is dedicated to in-vehicle telematics/M2M/IoT applications. So, you won’t find “desktop” on our box; these don’t hold up to the vibration, dust, and abuse of a vehicle environment.

CT650 uses our own custom build of Linux, leveraging the ease-of-use and versatility of an open system, while still providing for unique features. The embedded cell phone, embedded uninterruptible power supply, digital I/O, CANbus (SAE J1939), and multiple communication ports provide an all-in-one computer solution; no external converters or power supplies are required.

ControlTrac computers tie to the vehicle data bus (engine control module) and peripheral devices in order to monitor vehicle activity, operating parameters, and auxiliary sensors. Data may be communicated to the vehicle operator or transmitted by cell phone network or satellite.

Integrators

If the above makes sense, you probably recognize that CT650 is only one part of a larger system and integration project.

Dyacon onboard computers are sold to fleet service providers, which usually employ a team of software developers to provide a complete solution to the end users.

So, if you are providing asset management, road-weather information systems, mobile vehicle diagnostics, messaging, or routing information to fleet managers, Dyacon CT650 may be the right tool for your solution. ”

Eugene