Posts Tagged wireless

Industrial Wireless 101: Why do we need three frequency bands?

Regardless of what information you need to send, or where you need to send it, if your data is going “over the air”, you’ll need to choose a frequency in one of three ranges that do not compete with the FCC licensed bands for radio transmissions.

These three ISM (industrial, scientific, medical) bands are 900 MHz, 2.4 GHz, and 5 GHz. They’ve often been described as the industrial equivalent to Citizens’ Band radios, specified so they don’t interfere with broadcast radio signals.

History with technology would lead you to believe that the more Hertz you have, the better your radios will perform. But what you need to understand is that there’s a tradeoff. Each band has its strengths and weaknesses, and there’s a best use for each.

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Using a wireless radio battery to power a pressure transmitter

In an ideal world, every place you need to install a transmitter would have easy access to electrical power. But we don’t live in the ideal world, and there are locations where power isn’t readily available, and getting electrical power to those areas can be quite costly.

This was the situation at a local plant, in their flammable fuel storage facility. The site is required to keep a record of the line pressure that supplies water in the event of a fire.

The Problem

The water pipe is located 6 to 7 feet (2 meters) below grade, and the engineers planned to build a vault where they could install and maintain the necessary submersible pressure transmitter.

The planned location is more than 500 yards from any available power source. The signal coming from the pressure transmitter would have to run that distance plus an additional 200 yards to reach the control room.

Not surprising, the trenching cost for an electrical installation was quoted at a five-figure minimum price.

Finding a solution

The project engineer started considering a wireless solution, and then asked, “Can a battery-powered industrial radio also power a two-wire loop-powered pressure transmitter?”

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Having fun with a cellular modem

A wired bench sample of the Phoenix Contact cellular modem kitI just got my hands on a cellular modem that can stream analog data from a remote site to a SCADA/HMI/PLC/DCS/PAC, send a text message or an email on alarm, or receive a text message that can control a relay output (yes, it’s all secure ! !).  

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