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CANOpen Annoyances – I

Updated 12/14/2007 with more vendors

More notes added 4/19/2011

It’s obvious I like CANOpen, but it does have its downside. Areas that could be much improved include:

  • Too many connector types. OK, I can see a need for more than one connector type. But 20 types? Powering isolated CANOpen transceivers is not consistent either – I am going to design and build some interface boards to make it easier (results are here). Just giving examples from my favorite vendors:
    • My CANOpen interfaces both from Ixxat, Kvaser, ESD, Peak, and Grid Connect have DB9M CAN connectors, but do not provide any power. (The PEAK dongle can be easily modified to provide +5VDC on pin 1 and/or pin 9).
    • The DB9M connector seems standard for CAN interfaces – Kvaser, Ixxat, Softing, Peak, and Gridconnect all use it. The Ixxat USB/CAN interface has RJ-45 connectors, with RJ45/DB9 adapter.
    • The AMC DX15 uses a DB9M connector, and requires 7.5-13VDC on pin 9.  Current AMC CANOpen drives use dual RJ45s.
    • The Wago 750-337 has a removable screw terminal connector, and its isolated CAN transceiver is powered internally. (The 750-338 has a DB9 connector).
    • Copley Accelnet Panel drives (ACP-xxx-xx) use RJ-45 CAN connectors, and look like they need +5VDC on pin 8.  Copley ACP and ADP drives have a built-in DC/DC converter.
    • Copley Accelnet Micro Panel drives (ACJ-xxx-xx) use Samtec 10-pin crimp and poke connectors, and need power on pins 1 and 6.
    • IMS CANOpen MDrives (stepper motor + drive) use either DB9 or 5-pin micro (M12F) connectors, and look like they require 7-30VDC on pin 9.
    • Elmo’s Cello and Harmonica drives use a RJ-45 connector, are isolated, but don’t require external power.
    • Kollmorgen S200 Series uses 5-pin removable terminal block.
    • Technosoft IDM680 uses DB9M, and needs +24V.
    • Technosoft IDM240 and IDM640 uses what looks like a RJ-11 connector.
    • Faulhaber MCDC3003C and MCDC3006C drives use DB9M with no power.
    • Maxon EPOS uses a 4-pin Molex Micro-Fit connector, no power, and a Molex to DB9M cable available.
  • Raw CANOpen is pretty primitive – certainly not a good basis for rapid development. This is a bit better than I thought.
    • Copley’s CMO (ActiveX) is free for use with their drives. CML has a license fee which is reasonable. Both are higher level interfaces, and would make working with a Copley and Wago only system easier. However, as far as I can tell, the libraries only work with Copley drives and Wago I/O modules, so if you need to mix and match, it won’t work.
    • Elmo’s Maestro Multi-Axis Supervisor and Composer software look interesting (might make CANOpen development much quicker), but I’m pretty sure they only work with Elmo’s drives.
  • Software needs much more standardization – what works with what is still too restricted. To give some examples:
    • IMS requires Peak CAN interfaces (resold as the MD-CC500) to download firmware updates.
    • Copley’s CMO and CML software only supports interfaces from Copley, Ixxat, Kvaser, NI, and Vector, and only supports Wago I/O.  Setup can be done over serial or over CAN (except for Ixxat).
    • Elmo’s Interlude software supports Ixxat, Softing, and Kvaser.
    • AMC’s Driveware configuration and setup software works with CAN interfaces from Advantech, Ixxat, Kvaser, Vector, Port, Ifak, and ESD.  Newer AMC drives use a serial port for setup.
    • Faulhaber’s Motion Manager software only supports Ixxat.
    • Maxon supports Ixxat, Vector, and NI.
    • Wago appears to supply no software, just the EDS files.
  • Most CAN interfaces do not include CANOpen software – it’s either not available or is yet another cost (Kvaser was the exception IIRC). Softing includes a free CANOpen API (LeanCANOpen).  Go here for my current list of CANOpen software.

So if you need to mix and match (one of CANOpen biggest advantages), you are going to have fun. Think about a system needing a high power AMC drive, some Copley Accelnet Micro Panel drives, and some IMS MDrives. You’d need a Peak CAN interface to update the MDrives, but a Ixxat, Kvaser, or Vector interface to setup the AMC and Copley drives. You’d have to use different GUI software to setup the AMC and Copley drives. And you could drive using Copley’s higher level CMO or CML libraries with AMC and IMS, but there’s no guarantee that they will work (and I’m pretty sure no support). You would have to deal with different connectors (DB-9, RJ45) and different, incompatible voltages to power the CAN bus.



1 Qorin { 09.02.15 at 6:23 am }

Hi Tony,

I am working on a project with CANOpen from Copley-Accelnet.
I am wondering if the CAN bus in Beagle bone black is compatible with the CANOpen in the motion contorller? or some tweaking in the software for the protocol needs to be done??

I have never worked with a CAN system before. So if there is a mistake in my logic. please do tell me, so I can know my mistake

Best regards


2 Tony { 09.02.15 at 3:29 pm }

The BeagleBone’s CAN controller can work with CANOpen. However:
1. Since the BeagleBone only includes the CAN controller, you have to add a Cape with a CAN interface (or driver) chip. I have the Logic Supply CAN cape, but it is no longer manufactured. Some CAN capes are listed here
2. Of course, you have to correctly connect everything together; the Accelnets use RJ45 connectors, while the Capes typically use DB9M or terminal block connectors.
3. You need a CANOpen master software stack. Some people write their own. There are a lot of commercial stacks available. The most popular open source one is CAN Festival, but most likely it will require some work. If you need to get the BeagleBone working in a hurry, you should contact CAN Moveit, since they already have a CANOpen master stack with support for motion (CiA/DS-402) ported to the BeagleBone and claim their pricing is reasonable. You could also pay Copley for a CML license ($500 or $2500 I believe), but since Copley doesn’t support the BeagleBone, you would have to port it yourself.
4. You need to understand CANOpen. Using CAN MoveIt or CML would reduce the learning curve.

Good luck, and be persistent.

3 Qorin { 09.18.15 at 12:44 am }

Thanks! your reply gives me a clearer idea on what to do with the CANOpen.

4 Aaron { 11.12.15 at 2:08 pm }

Have you ever looked at AS-Interface Tony? CANOpen seems like a good choice for higher-level communication tasks, like talking to VFDs and to sensors with higher sample rates, and it’s particularly attractive if you’re into open, royalty-free standards and/or balk at the concept of even the simplest of machines having dozens of IP addresses. That said, for communication with lower-level sensors/actuators within the confines of a single machine/skid, I’m wondering if AS-i is a better fit. By lower-level, I mean devices such as proximity sensors, pushbutton enclosures, e-stops, door switches/locks, valve manifolds, soft start/quick exhaust valves, etc.

If you look at AS-i product offerings from manufacturers like Festo, IFM, and Pepperl+Fuchs, you’ll see options/capabilities that are mostly theoretical in the CANOpen world, especially when it comes to avoiding the need for separate safety-related wiring. AS-i also seems to have achieved better standardization from a standpoint of power distribution, whereas with CANOpen it seems like every other manufacturer is doing their own thing, or not. With AS-i, auxiliary power is basically there by default, whether you choose the standard flat cabling or daisy-chain your devices with M12 cables. I’m somewhat leery about the use of unshielded cabling in critical and/or industrial infrastructure, but for certain applications I haven’t seen an alternative to AS-i that isn’t some combination of exorbitantly expensive, super-proprietary, and overly complex.

As someone who has been casually following this blog for several years, I would be curious to hear your perspective.

– Aaron

Ps. When you have a moment, drop me a quick email. It would be nice to be able to exchange ideas in between your blog posts.

5 Steven Landau { 01.01.16 at 12:56 pm }

Aaron – Asi is great, for small digital data drops, – you still need accessory power for many of the network nodes. – analog is still lacking.

Asi with with analog specification was released 10 years ago. – where are the products?

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