Merging modern software development with electrons and metal
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Posts from — January 2008

Unique Products – Switchable Motor Power Supply

I like to highlight unique products that fulfill real needs. At work, our equipment is used both domestically and internationally, so it’s good to be able to easily switch between 120V 60Hz and 240V 50Hz. We like to use unregulated linear power supplies to power the motors, since they have good response, and are inexpensive.

So I went looking for a unregulated linear power supply with a switch to select either 120V or 240V windings, and found only one company that makes them – Logosol. Logosol’s 250W and 600W power supplies have an input voltage selector switch; both models also have separate motor and I/O power supplies, and the 600W model has an E-STOP input.

It’s possible to add a switch to an existing power supply, but that costs time and money, too, and results in a non-standard piece of equipment.

There don’t seem to be a large number of companies making unregulated linear power supplies – possibly because it’s easy to do yourself (if you can get an appropriate transformer) – I know of automation companies that build their own, but I don’t think it’s worth it at lower volumes, especially if you need certification. AMC and Acopian have wide ranges; others with fewer models include Logosol, Elpac, International Power, and IMS.

Since I’m writing about unique motor power supplies, IMS gets special mention – as far as I know, they are the only company to make a switch mode power supply specifically designed to power motors.  Unfortunately, they are single input voltage (120VAC or 240VAC).

Comments 4/20/2011: Copley Controls also sells switch selectable 120/240V linear motor power supplies, but I think Logosol’s are a better choice.

IMS (now part of Schneider) has dropped their switch mode power supplies (SMPS).

Carbur (sold by ASI in the US) does have some interesting SMPS for motors; see my blog post for more.

Tony

January 21, 2008   No Comments

Subversion and Other Version Control Choices

Version Control and Software Configuration Management Resources

In the end, good developers and good processes matter more than the tools. So here are two good sources for information and answers on version control and software configuration management: comp.software.config-mgmt newsgroup (low level of traffic, but I’ve seen some good conversations there) and CMCrossroads.

Commerical Version Control Software

A few years ago, I did an extensive look at commercial version control software. The two I was most impressed with were Perforce and AccuRev. Perforce is a traditional VCS, with a reputation for speed and good support. AccuRev has an innovative approach (streams) . Both are worth consideration, but are $750/developer or more, plus yearly maintenance fees. At work, I’ve been very happy with Subversion, but Larry O’Brian has seen some speed bumps.

Subversion

I’ve been using Subversion, and have been very happy with it. I still think it is an excellent version control system for most automation companies, and I will be doing a series of blog posts using it. Some of its good points:

  • It’s free (and open source)
  • Its centralized approach fits the model of most automation developers (unlike open source projects, which tend to be highly distributed).
  • It runs well on Windows (unlike some open source version control systems)
  • It has good, free documentation
  • It is widely available for hosting (for example, it’s the only VCS available on Webfaction’s Control Panel)
  • It has excellent tool support, including on Windows
  • It is constantly updated (V1.5 will have substantial improvements)

Innovative Version Control Systems

The open source version control field has been very fertile, with several innovative approaches. I’d say the open source side has been more innovative than the commercial side. The ones that have caught my attention are git (of Linux fame, and right now probably the “hot” one), darcs, mercurial, and bazaar-ng. All of these systems are designed for distributed development, unlike most version control which is based around a central server. Later I plan on looking into them in-depth, and trying one out – I have a few project ideas that would benefit from a more distributed approach.

Tony

January 18, 2008   2 Comments

I’m happy with Webfaction hosting

I’m not a salesman, but I am happy enough with Webfaction‘s hosting that when I move to WordPress 2.3 I plan on adding a referral link.

What’s nice? Now even the lowest priced plans include plenty of applications, and a good amount of bandwidth, disk space, and memory. I haven’t had any hosting problems since I’ve started.

Webfactional’s Control Panel makes it fairly easy to manage my site. If you want more control, you have to get familiar with command line Linux, but the Control Panel makes it easy to setup basic WordPress, Subversion, and Trac sites.

These features and the price make Webfaction an excellent solution for an individual (like me) or small business wanting to setup up subversion and trac sites.

Tony

January 16, 2008   No Comments

Trac and Subversion sites are up

Webfaction dramatically improved their hosting plans, making it easy for me to add more applications.

So I’ve added a Subversion (svn) repository and a Trac site to this site. Right now they are pretty empty, but I will be adding to them over time.

The svn repository will host my blog project files, and will be used for posts on using version control. The Trac site contains additional information related to this blog. Both sites are read-only – I don’t have time to deal with link spam, wiki spam, or polluted repositories.

The svn site is http://svn.factoryswblog.org It will redirect a web browser from http, but not a client (such as my choice, TortoiseSVN ).

The trac site is http://trac.factoryswblog.org It will redirect from http.

Note that since I’m not paying extra for my own SSL certificate, you’re going to have to trust me (accept the browser pop-ups) if you want to use the sites.

Note 4/20/2011: my svn and trac sites are http; https was a fun experiment, but not necessary for this site.

Tony

January 16, 2008   1 Comment