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Posts from — February 2008

Open Source Version Control Comparision

JavaWorld has a hands-on overview of CVS, Subversion, Mercurial, and Bazaar here.

Note 4/21/2011:  I’d say the most popular open source VCS’s are:

  • For centralized, Subversion
  • For distributed (DVCS), git (most popular) and Mercurial.


February 25, 2008   No Comments

Review: Embedded Networking with CAN and CANOpen

Embedded Networking with CAN and CANOpen by Pfeiffer, Ayre, and Keydel, RTC Group /Annabooks Copperhill, 2003.

Summary: 8.5/10, highly recommended.

The book covers the CANOpen basics well. It helps that I’m already familiar with basic CAN and CANOpen concepts (SDO, PDO, Object Dictionary, etc), but the explanations are clear, and the authors do provide concrete examples, which always helps.

The book does go into some low level details, such as CANOpen message formats. That’s good knowledge to have – I’ve never regretted learning about computing at the bit level. If you need really detailed information about CAN, then you will need another book.

The final part of the book is a CANOpen summary. I expect to be using this section quite a bit as I continue experimenting with CANOpen.

I don’t have real complaints about the book. I do wish, however, for a complimentary book specifically about CANOpen in factory automation. For example, this book does not cover DS402 (drive profile) at all.


February 21, 2008   No Comments

Fieldbus Book Wars

Notes 4/21/2011: I’ve updated the links and status (but not the chart); both CANOpen books are now available.  Sometime I’d like to revisit field bus books, but it’s not a high priority.

One way of judging programming language popularity is to compare book sales. So I decided to do something similar – see how many books in had the names of popular fieldbuses in their title. I excluded non-English books (German Profibus users get more choices) and standards documents.

Fieldbus In Print Out Of Print Total
CANOpen 0 2 2
Profibus 2 1 3
Profinet 1 0 1
Foundation Fieldbus 1 2 3
Devicenet 0 0 0
Ethernet/IP 0 0 0
EtherCAT 0 0 0
Ethernet PowerLink 0 0 0
Modbus 0 0 0
Modbus/TCP 0 0 0
CC-Link 0 0 0

I wouldn’t choose a fieldbus on the basis of books; for example, many of the fieldbuses have good information available on the web. But it’s interesting to look at the book titles and year of publication:

Apparently fieldbus books do sell: several recent books are already out of print (or otherwise unavailable).


February 20, 2008   3 Comments

A 19th Century Tech Bubble

I really enjoy late 19th and early 20th century English literature – not just serious authors like Evelyn Waugh who never go out of print, but also the rivals of Sherlock Holmes. The internet (especially project Gutenberg) has made available many books I have not been able to find in print.

Since I lived in Silicon Valley during the dot-bomb bubble, I always get a kick out of reading Arthur Morrison’s The Affair of the “Avalanche Bicycle & Tyre Co.,Ltd.” Although it was written in 1897, it sounds just like the internet bubble. The story appears in the Dorrington Deed Box, which is now back in print – and available online.


February 13, 2008   No Comments

“A Bad Technician Is Worth Negative Money”

“A Bad Technician Is Worth Negative Money” is something I said a lot back in the days when I had to go around and fix all the stuff the night shift technician had screwed up. A technician who causes problems is worth negative money because not only does he not do his job, he sucks up the time of others who must fix his mistakes.

Larry O’Brien comes to a similar conclusion about software developers: bad programmers are not slow programmers – they are programmers who are actively counter productive to the code base. In a fascinating post, he argues that the goal isn’t a silver bullet for programmer productivity, but a silver codebase, which bad programmers make impossible. Larry started all this discussion by dissecting the myth of the super-programmer.

My take – he makes sense to me. I’ve had to clean up code from some, well, people who shouldn’t have been programming, and it was not pretty. I’ve seen how a well designed codebase can make adding functionality much easier. On the other hand, I currently have an inherited codebase that needs some serious refactoring before it’s anything close to silver.


February 1, 2008   2 Comments