Well, the airplane seat wasn’t big enough to comfortably use the computer. So, I settled for listening to Gary Mintchell’s podcast and then opened a novel. But Saturday afternoon’s low scoring Arizona Diamondbacks’ game gave me time to write. Herewith, some recommended reading on fieldbuses, wireless, and Industrial Ethernet. Plus some “pot-stirring”?
“Fieldbus in biopharma applications, Part 1” in Control magazine is by a user that chose four fieldbuses for their application. There are some great pictures of discrete wiring vs. fieldbus wiring. Their driving factor was space savings:
Other attributes of fieldbuses, such as their capability to help with predictive maintenance, weren’t as tangible at the outset, but could be explored and exploited after startup and commissioning. The main task at the outset was to have all this equipment fit in the space available, and fieldbus technology was a means to this end.
They achieved their main goal.
Another interesting comment:
Clearly, one fieldbus doesn’t get us there, but maybe someday that will be a reality. I think, at best, given the timeframe of our project, we could have reduced the bus count to three, and, today, maybe to two. Live and learn.
I don’t know which two they had in mind but clearly PROFIBUS and AS-i could do it. PROFIBUS DP and PROFIBUS PA have one protocol but two different physical layers. The advantage is that the same engineering tool works for both.
“Delivering on the promises of fieldbus” in InTech was written by *** Caro. He opens it: “Suppliers need to support Foundation fieldbus high-speed Ethernet to achieve the potential of fieldbus. They’re not doing that.” That may be true for Foundation Fieldbus, but maybe not. PROFIBUS PA can be integrated into PROFINET. And work is proceeding to make it even easier. Any fieldbus can be integrated into PROFINET using a proxy. Proxies already exist for many fieldbuses. And dates have been announced for a PROFIBUS PA proxy, an FF proxy, and a HART proxy.
No doubt wireless is a factor and becoming more of one. I think there are different types of wireless as I’ve blogged before. This article from Control doesn’t really differentiate them, but it’s worth a read anyway: “Cutting the wires of communications.”
ARC has published a new study. I haven’t read the study, but the pitch for it is interesting. In fact, just the title is telling: “Use of Wireless Technology in Manufacturing to Grow 26% Annually.”
“Ethernet-device invasion stuns” is a short article in InTech that makes some good points.
The Industrial Ethernet Book published “Using Ethereal Diagnostic Tools for Network Troubleshooting.” This is especially interesting for PROFINET users as Ethereal includes the ability to examine PROFINET packets. Ethereal has recently become Wireshark.
You will find an interesting exchange about Ethernet/IP and PROFINET on the Automation List about motion control. That old chestnut “proprietary” gets tossed around and addressed well be a couple of contributors.
My new friend Nick Belardes on the ProSoft blog calls this “the pot-stirring PROFIblog.” Maybe… but my real goal is to raise the visibility of fieldbuses in general and PROFIBUS and PROFINET in particular. Granted I’m passionate about that task. And that somehow translates into feeling it to be my duty to “correct” misstatements about fieldbuses, PROFIBUS, and PROFINET. Kinda reminds me of Miss Piggy’s comment: “Beauty is in the eye of the beholder, and it may be necessary from time to time to give a stupid or misinformed beholder a black eye.”
Ok, the stage is set and the stirrer is in hand. Let’s look at Jim Pinto’s column in Automation World: “The dichotomy of open standards.”
He starts from a premise I disagree with: that there should be just one fieldbus. My position is: “The Great Thing about standards is that there are so many to choose from.”
Let’s examine this paragraph in some detail:
Some vendors pretend that they are simply giving away their technology freely for everyone to utilize when in reality they are encouraging others to use it as a standard. One example is Profibus: Siemens is the original developer of Profibus and continues to gain advantage through its proliferation (Rule 2). And, Siemens continues to sell Profibus chips (Rule 1). Meanwhile, the followers believe that what they support is indeed “free and open.”
Let’s ignore the pretending part and correct the notion that PROFIBUS is a Siemens technology. PROFIBUS development began in 1987 by 13 companies and 5 universities. Today the development is advanced in various working groups. For PROFINET alone there are more than 100 engineers from over 50 companies participating in 22 working groups. Siemens is obviously a big part of that, but they are far from alone. There are many installations with no Siemens content. In fact there are installations with Rockwell PLCs using PROFIBUS. [This also refutes his earlier comment: “End-users continue to ask for interoperability as a means to achieve vendor independence.” This is already being done!]
Siemens does sell PROFIBUS chips, but so do other companies… and because the standards are published, additional companies will develop PROFIBUS chips. (The same is true for PROFINET.)
Maybe the “followers” believe that the technology is free and open is because it IS free and open.