Application Example - 900 MHz Wireless Delivery of Industrial Process Control Signal

We have a new video with an application example where wireless signal transmission provides a powerful solution. You can always get help with your applications by contacting us.

Two-Wire vs. Four-Wire Transmitter For Analog Process Measurement and Control Signals - What Really Matters?

One of many form factors of two wire transmitters
for industrial process measurement and control
Courtesy Telmar Instruments

Transmitters are everywhere in process control. They take a sensor output signal,amplify and condition it, then send it to monitoring and decision making devices. The most common analog electrical signal used for transmitting process control signals is a 4-20 mA (milliampere) current flow. It has succeeded in its adoption for a number of reasons, not the least of which are its resistance to interference and ability to transmit a signal across a substantial length of cable.

Aside from the sensor connection, there are two basic wiring schemes for these devices. The simplest employs just two conductors to transmit the signal and coincidentally provide operating power for the transmitter electronics. This type of transmitter is commonly referred to as a "loop powered" or "two-wire" device. A DC power supply, typically 24 volts, is wired in series with the 4-20 mA output signal and the transmitter derives its operating power from this source. Loop powered devices generally consume very little power, but process designers must consider the total resistance imposed on the loop by all connected devices. The cable, unless the length is monstrous, poses a measurable but comparatively small resistance. Careful consideration should be given to the resistance imposed by receiving devices, especially if there are several in series, receiving the loop signal. The output voltage of the power supply and the maximum tolerable voltage of the connected devices will serve as limiting factors on loop instrument quantity. Where they can be applied, two-wire transmitters offer a straight forward solution for delivery of analog process measurement signals.

A "four-wire" transmitter gets its name from, you guessed it, the two pairs of wires used to provide operating power and a signal transmission path. Provided with a separate power source, possibly even 120 volts AC, this transmitter type will often be found in applications where the sensor may have power requirements that cannot be met with the limitations inherent in the loop powered device. While it may seem that the separate power supply negates the need to consider total resistance load on the signal loop, this is not the case. The signal loop still will be limited by the DC power supply that serves as the driving force of the loop.

In many cases, the question of "two-wire or four-wire" will be answered by the transmitter manufacturer. Since the two-wire scheme is a less burdensome installation, it may be the only product offering when a suitable device can be designed for an application. That said, a diligent search will probably find two and four-wire versions of transmitters for almost every application.

What are some decision making guidelines?

• Some types of transmitters have sufficiently high power requirements that they cannot be loop powered. In this case, four-wire may be the only option.
• For low resistance loads, use 2 wire transmitters for a simpler installation.
• Allow some headroom in the loop resistance to accommodate at least one added receiving device in the future. For example, a temperature signal may serve as an input to a controller now, but need to service a recording device potentially added in the future.
• Distance should not be mindlessly overlooked, but is generally not a limiting factor, as most installations would be compatible with the distance limitations for two- or four-wire device output signals. 
• When signal transmission distances become unwieldy, due to cabling costs or other factors, consider a wireless transmitter instead of a wired device.

The important aspect of applying 4-20 mA signal loops is to maintain the capability to add another receiving device to the circuit. The use of information in the form of process signals has been growing for a long time and is likely to continue. It is certainly easier to wire an additional device into an existing loop, than to install an additional sensor, transmitter, power supply, and cabling to accommodate the additional device. 

Analynk provides wired and wireless solutions for delivering analog process control signals. The wired devices carry the company's Telmar brand name. Wireless solution products carry the Analynk and Sensalynk brand name.

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Creating Wireless Process Connections Is ABC Simple

Industrial wireless is not new, it is a mature technology. With the products available today, implementing a wireless process signal connection is no more difficult than installing a simple process controller. Analynk is a part of that simplicity, manufacturing modular receivers, transmitters, and companion products enabling operators at any scale to effectively deploy a 900 MHz or 2.4 GHz wireless solution.

There are many instances where a wireless solution provides distinct advantages over wired installations. Understanding the simplicity of wireless installations, and that product based solutions are readily available, can unleash your ingenuity at solving process control challenges using wireless communications. A previous article may help you recognize opportunities to avoid expensive or difficult cabling, or actually make connections you thought were impossible.

Let's look at a basic installation that measures temperature at a remote location (the measuring station) and transmits the signal to your office (the monitoring station).

Here is all you need:

• Power supply to operate the temperature measurement instrument and the Analynk transmitter. Analynk transmitters consume little power and can be provided with photovoltaic power supplies, if needed.
• Temperature measuring device of your choice with 4-20 ma output signal and up to two discrete outputs. It does not need to be wireless. 
• Analynk transmitter located at the temperature measurement station to convert the 4-20 ma temperature signal to digital format and send it to the monitoring station. The connection between the temperature measuring device and the Analynk transmitter is wired.
• Analynk receiver located at the monitoring station to receive and decode the signal from the Analynk transmitter, converting it back to 4-20 ma. A wired connection between the receiver and your monitoring or recording equipment delivers the 4-20 ma temperature signal to its destination.

The simple wiring connections to the transmitter and receiver differ little from those of most other devices (see the ABC’s on the illustration).

A - Connect a power source to operate the unit
B - Connect the input signal (if it's a transmitter) or output signal (if it's a receiver).
C - Connect discrete inputs (if it's a transmitter) or outputs (if it's a receiver).

Wiring diagram for Analynk Model A753 wireless transmitter

Setting up the transmitter and receiver takes no more technical knowledge than other modern control devices. You follow instructions to set a few parameters, calibrate, and put the system into operation.

You can gang inputs and outputs together with an expander module and use a single transmitter and receiver to deliver multiple sensor signals. All units are DIN rail mounted with removable terminals for simple, organized installation and replacement.

Wireless connections can expand your operating capabilities, as well as business opportunities. Analynk has made the implementation easy. Use your creativity and ingenuity to bring new applications to your operation. Contact Analynk anytime to discuss your ideas or get the help you need to put your ideas into action.

Process Monitoring and Control - Where You Can Make Good Use of Wireless

Analynk empowers industrial process operators at any scale to bring the functional benefits of industrial wireless communication to their applications. The company provides easy to implement wireless hardware solutions that can be economically applied to even as single data point.

Talk a look at our short video for some application suggestions. Ramp up your ingenuity and develop ideas for your facility or operation. Contact the experts at Analynk for solutions. We enjoy hearing new and creative ideas for meeting process control challenges with wireless.

Outlook for 2016

At Analynk, we are wrapping up a very good year, and extend our sincere thanks to our customers, vendors, and others that have supported our continued growth and success in the industrial wireless communications field.

We brought several new products to the market this year, including some new versions of the Hazardous Area Wireless Access Point Enclosure and our patented Explosion Proof Antenna. The coming months will see the release of some new products we have been working on this past year. Stay connected with us and you will be among the first to know about them.

We hope your year was as good as ours, and wish everyone a safe and happy holiday and prosperous New Year.

Wireless Linkup For Hazardous Gas Monitor

Hazardous Area Gas
Detection Units on Assembly Line
Courtesy Starcom Solar

Analynk Wireless manufactures industrial wireless signal transmitters and receivers to accommodate a broad array of industrial process control applications. The company was selected by Starcom Solar, Inc. as the provider of the wireless communications section for their innovative portable and fixed installation hazardous gas monitoring stations. In addition to transmitter modules, the Starcom monitoring station utilizes Analynk's patented antenna for use in hazardous areas.

The wireless communication capability enables deployment of the monitoring system on mobile units or remote installations. Analynk's standard transmitter range extends up to 20 miles. New versions will soon be available with Iridium, GPS, and GLONASS satellite linkups enabling worldwide signal transmission and reception. Variants include capabilities to transmit a variety of inputs,
including 4-20 ma, switch closure, thermocouple, and RTD.

The Analynk product line of wireless transmitters, receivers, and antennas provides broad capability and is easy to apply and integrate into any installation. You can find out more about the A753 Transmitter in the data sheet included below. Share your signal connectivity challenges with a product specialist and see how easy and effective a wireless solution can be.

Analynk A750 and A753 Industrial Wireless Transmitter and Receiver from Analynk Wireless, LLC

Will Wireless Work For My Process Control Application?

Model A750/753 Wireless Demonstration Unit

Wireless transmission of process measurement and control signals has not been new technology for quite some time. That said, there still remain many facilities where it has not made any inroads yet. When technology is new to the industrial market, especially if it challenges the current way things are done, early adopters with larger scale, higher dollar operations are needed to put the technology into practical use and generate manufacturing volume for the technology producers. If deployment of the technology proves beneficial, the market grows on the consumer and producer sides. With greater efficiency and scale, the trend for the technology costs tends to decrease, while the range of feasible applications and projects grows.

Wireless communication for industrial applications is well beyond the point of early technology adoption. Protocols are in place, products for the transmitting and receiving of wireless process signals are mature. As a designer, engineer, manager, or operator of a process, you should confidently consider wireless connections between measurement and control or recording devices as part of any new installation or upgrading of existing facilities.

Regardless of what I have just written, sometimes we just need to see things work before we can make the leap of adoption. New ways of doing things bring the promise of reward, but also the concern of the unfamiliar.

Analynk has a solution for you.

Analynk's wireless demo kit includes a model A750 receiver and A753 transmitter both housed in NEMA 4 enclosures. The kit operates at 900 MHz with full 1W power. Locate the transmitter and receiver at points where you wish to establish a wireless connection. You can provide your own input signal, or use the provided simulator to show that a wireless connection can be established and function in a manner that will give you confidence to move forward with implementation. The kit is useful for testing out possible new locations for distance and signal strength. You will use it as wireless communications expand through your facility. Test the location first, then order the needed wireless equipment. It's a solid and low risk solution.

Analynk is a manufacturer of both wireless and wired devices for process measurement and control. The company's offering includes a wide array of standard products, as well as integration and customization to meet specific project requirements. Contact the specialists at Analynk to discuss your industrial wireless application requirements.

Analynk Industrial Wireless Demonstration System from Analynk Wireless, LLC

Out of the Box Thinking Delivers Benefits with Industrial Wireless Test Station

Tire manufacturer used wireless technology
to improve output

Wireless network communication has enjoyed continuously increasing rates of adoption in the industrial process control field for a number of years. Protocols and methodologies are generally well established and a wide range of products are available, making it less challenging to configure an application solution. As the manufacturers of industrial wireless devices have gained production efficiency and responded to an increasingly competitive market, the cost of implementing a wireless solution has become less of a barrier. Truly, industry is now in a phase where creativity and ingenuity will bring changes to traditional process and production operations to take full advantage of the untethering of many common measurement and control devices.

Traditionally, most measurement and control instrumentation was fixed in place by piping or cabling. While that is still the case throughout much of the industrial sector, opportunities are continuously emerging for wireless technology to provide improvement in performance and efficiency. I came across an example of how one manufacturer of tubeless tires devised a wireless test station to replace their existing wired version to:

• Reduce maintenance by eliminating signal cables and power cables. No more cable damage from moving wired transmitters around the tire test area. 
• Replace manual data logging with remote automatic data logging. 
• Maintain or increase the accuracy of each measurement point. 
• Allow a single test station to be employed easily at multiple locations throughout the factory. 

This was accomplished using readily available pressure transmitters, wireless transmitters, access points, receivers, and related hardware to provide a complete measurement system delivering test and measurement data to a remotely located data logger.

Use your creativity, your ingenuity. Get outside the box and examine your industrial process or production operation. Look for opportunities to sharpen your efficiency and improve outcomes. The prospects are good that there may be more gained from a wireless installation than the mere absence of cabling. Discuss your ideas with a wireless product manufacturer, solicit their recommendations, and evaluate the potential benefits to your operation.