Archive for category Wireless
In the past month, I’ve focused several articles on industrial wireless technology. If you’re interested in learning more, here are several webinar recordings you can watch on your own time that will give you more insight into how wireless works, and how companies are using it to extend that measurement base and get process information where they need it to go, even on a limited budget.
In our continuing quest to understand industrial wireless, here’s the next bite. We already talked about the three industrial wireless bands and what they’re used for. Now, we’ll look at wireless antenna.
The antenna’s primary purpose is to focus or direct the signal that it is sending or receiving. The antenna strength, called gain, (measured in decibels) concentrates the transmitter or radio signal in a given direction, and reduces it in unwanted directions. The higher the antenna’s decibel value, the more focused the signal.
I’ve found that the word gain sometimes confuses people: they think gain refers to an antenna ADDING power to a radio. That’s actually what an amplifier does. Antenna gain is about concentrating or dispersing radio frequency energy and directing it where it needs to go. By packing that available energy into various patterns, as the different antenna types do, a radio signal can be spread out to a broad field or concentrated into a small tight pattern to go a farther distance.
Just like the three industrial wireless RF bands, there are three main types of antennas. And while lots of people have tried to explain them, with technical charts and inkblot-style diagrams, this simple description really hit home to me:
- Omni-directional antennas radiate their signal in all directions, like a floor lamp radiates light equally around itself.
- Semi-directional antennas radiate in a specific direction across a large area, like a spotlight shining on stage.
- Highly-directional antennas focus their signal on a very specific target, like a laser pointer focusing on a specific portion of a photo.
So, let’s take it a step further.
We keep a Honeywell XYR6000 field transmitter network setup at the Lesman offices for training, customer demonstrations, and site surveys. And part of my job is to keep the system in working order.
Honeywell releases incremental firmware updates when they need to fix a bug or add functionality to the systems. I’d downloaded both the 201.1 and 202.1 update files from the Honeywell website, but had procrastinated in doing the installation. (Never happens to you, right?)
When I got around to doing the updates today, I pulled out the wireless device manager (WDM) manual [1.8MB PDF]. and turned to section 6.2, page 131. It has about 10 pages of step-by-step instructions on the update/upgrade process.
But then, I found myself wishing for another of those “missing pages from the manual”. While it has all the steps, here’s what’s missing: A map that tells me how long the steps take.
This morning, I came across two articles I thought were worth sharing. They’re both about industrial networks, but from two entirely different angles.
The first article is written by a network engineer at a manufacturing plant. The gist of it is something we at Lesman talk about often with our customers: Buy what you need. In this case, he’s talking about Ethernet switches for light manufacturing and assembly operations, where a field-hardened industrial ethernet switch may be overkill (and out of your budget).
The situation: Plant operators needed notification and a log of events or alarms happening at a remote pump station, 17 miles away.
The options: First, the engineers considered installing dedicated leased phone lines with modems. But when one engineer asked if anybody really remembered or understood the AT codes the modems used (back in the early Internet days), and noone did, they dropped that option. Next, they investigated license-free wireless. That proved impractical: There were hills and valleys between the plant and remote station (no line of sight), and they’d have to lease property between the two locations and install repeater towers at an additional expense.
So, how did they get the data across 17 miles without leasing land or resurrecting obsolete technology? The answer was much simpler and less expensive than they anticipated. Read the rest of this entry »