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Cool Stuff: Fieldbus Finder by Sick Sensors

Sick sensors has a really cool web page showing their products sorted by supported fieldbus.  It’s simple:

  1. Find the fieldbus you’re interested in; choices include CANOpen, DeviceNet, EtherCAT, EtherNet/IP, HIPERFACE, IO-Link, Modbus TCP, Profibus DP, Profinet, PROFIsafe, and SSI.
  2. Find the component type you’re interested in.  What’s available varies with the fieldbus; for example, only measurement and feedback sensors are available for the SSI and HIPERFACE encoder buses.
    1. However, the major fieldbuses have a lot of available types, typically including absolute encoders, bar code scanners, 2D code readers (for Datamatrix and such), laser measurement, linear measurement, light curtains, network gateways, RFID, safety controllers, safety laser scanners, and hand-held scanners.
    2. Sometimes, adding fieldbus functionality requires a gateway module, or an external communications module.  From a glance, it appears most safety communications (e.g. to safety controller) and most EtherCAT communications require a gateway — and those gateways can be pricey.
    3. Still, Sick’s level of fieldbus support is impressive.
  3. Then a new tab appears with search results for the component type, already filtered by fieldbus type.

September 3, 2013   No Comments

Photonics West 2013 Notes

I visited the Photonics West 2013 show recently.  I saw a lot of cool equipment there, but I was looking for automation equipment, not at lasers, light sources, optics, or such.  So here are my notes based on my short and highly unscientific visit:

Piezo Motors and Stages

Piezo motors were everywhere.  I spent some time taking a look at SmarAct’s wide variety of piezo positioners (which range from tiny to small), rotary tables, end effectors, systems, and controllers.

New Scale was showing their tiny piezo powered autofocus lens and actuators.

Other piezo companies at the show included attocube (piezo positioners), npoint (piezo stages), Cedrat and their US Distributor, MMech, PI, piezosystem jena, and Mad City Labs.

Visit my Piezo Motors and Piezo Positioners page for a more complete list of piezo motion companies.

Motion Control, Encoders, and Stages

AllMotion displayed their tiny servo and stepper drives.  They are working on adding fieldbus support, which is a very good thing (I do not like their current communication protocol).  I’ve recently used their servo controllers in a project, so I’ll have more to say later (hopefully, not too much later!)  A neat trick: if you use single row 0.1″ receptacles, you can mount their drives upside down to a custom PCB, no cables required.

Of course, you’d better make sure you layout is correctly positioned — and all your connections are right!  I’m glad I didn’t do this, because I ended up with the motor turning in the opposite direction; the fix was simply swapping some wires on the cable wiring diagram, instead of re-doing my PCB.

Zaber demonstrated a wide variety of stages and USB or serial controlled stepper drives.  Their protocol is pretty simple; it uses a 6-byte command structure.  It looks better than a lot of screwy ASCII protocols, but I still prefer standard fieldbus protocols (CANOpen, Ethernet Powerlink, or EtherCAT).

I had an enjoyable time talking about Canon’s encoders.  They’ve dropped some of the models I remember from previous years, but still have unique optical encoders that use a laser light source instead of a LED.  Pricing for the linear encoders is reasonable; the laser rotary encoders are considerably more expensive (but they also provide higher performance).

The Siskiyou people impressed with their passion for making mechanical components such as optical breadboards and lens holders.  They offer motors to replace manual adjust screws and motorized stages for microscopes.

Cameras and Lenses

I always stop by Vision Components, since I’ve know their US salesman, Endre Toth, for a long time.  VC makes OEM smart cameras; you can program them yourself using VC’s software, use Halcon, or other third party software such as the EyeSpector.  My favorite products were:

  • An all in one inspection smart camera with multiple lighting options.  Most smart cameras with built in lighting have only one type; often different types are needed.
  • The VC nano cube.  OK, I wish the camera cables had latching connectors, but the IP67 remote head looks great, and reminds me of the unique M40/M50 line of cylindrical smart cameras.
  • The VC nano 3D triangulation based 3D smart camera.

Mr. Toth also represents Vision and Control in the US; V&C has some interesting products such as telecentric lighting.

I also enjoyed talking with Point Grey (who make a variety of compact, competitively priced cameras with USB, Ethernet, and Firewire interfaces) and Varioptic (makers of liquid lenses, used in a variety of products including 2D barcode readers from both Cognex and Microscan).

Other Cool Stuff

I enjoyed playing with an impressive 3D model, made by an additive 3D printing powered by TI’s DLP technology.  There were a number of other companies showing off MEMS micro-mirrors, but I didn’t record their names (I’m trying to be realistic; I find micro-mirrors fascinating, but I’m unlikely to ever design a product using them).

Nanoscribe’s technology is even more impressive: they can make a model of the Eiffel tower that’s 100 microns tall.

February 20, 2013   No Comments

A Less Expensive Magnetic Linear Encoder

I haven’t found the linear encoder promised land I was looking for, but recently I did learn a bit about some reasonably priced linear encoders: Turck’s LI20 and LI50 hall effect based magnetic linear encoders.

The LI20 is available with 10 micron resolution, and handles speeds up to 25 m/sec.  The LI50 is available with 5 micron resolution and speeds up to 16.25 m/sec (although at 5 microns, max speed is about 3 m/sec).

If I have my part numbers and PLC Center pricing correct, a T8.LI20.1111.2050 with 1 meter encoder strip (magnetic band) would be about $315, and a T8.I.LI50.1111.2250 with a 1 meter encoder strip would be about $430.  (For the magnetic band, I’m assuming buying 90 m (T8.B1.10.010.0900 or T8.B2.10.010.0900) and cutting into 90 pieces each 1 m long; it looks buying shorter lengths is considerably more expensive per meter).

Note 5/10/2010: Honeywell also makes affordable magnetorestrictive linear encoders, although I don’t think they are well suited for typical industrial automation applications.  Minimum resolution is 140 microns, length is 75 or 225 mm, and output is analog or RS-232 (225mm only).  The SPS-L225-HALS (225mm analog) is about $250.

November 13, 2010   No Comments

Where are the inexpensive magnetic linear encoders?

In an article in Control Engineering, Steve Feketa of Rockwell claims that magnetic linear encoders are available for $200 for a 1 meter encoder, while optical linear encoders can cost up to $2000 for a 1 meter encoder.

If you’re paying $2000 for an optical linear encoder, you’re either getting a very high resolution encoder, a very rugged encoder, or some golf at the country club for the encoder manufacturer’s sales team.  I can buy a nice optical linear encoder with a 1 meter scale for substantially less than $1000.

But I can’t find any information on inexpensive magnetic (or magnetorestrictive) linear encoders.  I do know of inexpensive optical linear encoders from US Digital and Avago that are under $200 for 34″, but they are hard to mount and the resolution is only 12.7µm.  I found that Heidenhain, Renishaw, Netzer, and Temposonics (magnetorestrictive) all make magnetic linear encoders.   I couldn’t find any pricing, and I’m not going to spend a lot of time trying to get quotations when I’m not ready to buy one.  I suspect that Netzer is the only one that might be close to $200 for a 1 meter length.  OK, New Scale Technology’s Tracker is probably under $200, but its length is only 8mm.

Why am I interested in low cost linear encoders?  Because the current cost of linear restricts their use to when I really need them (I’ve used linear encoders twice in > 10 years of machine building).  Even a low resolution linear encoder is helpful to minimize problems from backlash, and to provide feedback for linear motors.

For the hobbyist, eBay is one solution.  I recently bought two MicroE M2000 linear encoder read heads + electronics on eBay for a very reasonable price.  True, I don’t have the scales, but I’m not sure where I’ll use them, so that’s OK.

July 10, 2009   1 Comment