Merging modern software development with electrons and metal
Random header image... Refresh for more!

Posts from — August 2007

Why use a standard such as CANOpen?

What is the big advantage to using an open standard such as CANOpen? In a word, interoperability. You should be able to mix and match CANOpen products from many different vendors. This has many benefits such as:

  1. Reduced dependence on any one vendor. If a vendor goes bankrupt, stops making a product line, or increases its prices, it’s much easier to replace it with a similar product based on the same standard. For example, an AMC drive is not a drop in replacement for a Copley, but it’s a lot easier to swap them than, say, replace MEI PC/DSP motion controller with a Galil machine controller.
  2. Much wider range of products available. For example, many proprietary distributed drive manufacturers do not sell I/O. Or they only sell low current or low voltage drives.

Of course, not everything is perfect. There are not CANOpen products for every need. Combining CANOpen products is not as easy it should be. I will write about specific examples later.

Tony

August 22, 2007   No Comments

CANOpen Surplus Goodness

My CANOpen devices

Well, it’s not all surplus, but most of the system was bought surplus. I will be writing about my experiences learning how to use CANOpen.

The lineup:

Comment 4/7/2011: I have a lot more CANOpen equipment now; eventually I will get around to dissecting it.

Tony

August 10, 2007   No Comments

Logosol Surplus Goodness

Logosol Distributed Drives

Above is a picture of my current Logosol network, consisting of a serial to RS-485 adapter, LS-173-B drive (motion controller + server amplifier), and a LS-182X5P-1210 drive.

Logosol’s distributed control products are quirky to program and the documentation is horrible. Support is fine – when I’ve had to call, I have received good answers. Pricing is pretty good. The products have really improved over time; the LS-173, for example, only handles single ended encoders, while the latest models handle differential encoders. Most of the more recent models (including the LS-182) support Panasonic’s lovely S-series, which Panasonic has unfortunately quit making.

Another big quirk in the early models (such as the LS-173 and LS-174) is that they do not remember their settings, including the error actions. So if you want the drive to stop after it reaches a limit sensor, you have to specifically send a command to set that mode every time the drive is powered on.

Early models (e.g. LS-173) also do not have separate control power (for the motion controller) and motor power. So if you want to have an Emergency Stop, Light Curtain, or other safety device turn off all power to the motors, it will also turn off the controller. This of course makes it more difficult to ensure the drive is correctly setup at all times. It also means you will have to re-home the system, because the motion controller will not be keeping track of the motor’s position while the motor power is off.

Logosol has told me that newer models such as the LS-132 remember their settings. Newer models such as the LS-132 have separate power connections for the controller and the amplifier.

Another plus is the completeness of their distributed lineup – besides servo drives, stepper drives, servo drives with stepper inputs, spindle motor controllers, and high power I/O, they have the only distributed servo controller with an analog output (-10V to +10V) that I know of. It may sound strange to want to use a separate servo amplifier with a distributed control system, but sometimes it is necessary. For example, Nanomotion’s piezo motors only work with their servo amplifiers.

Tony

August 10, 2007   No Comments