CAN Bus Communication

Yep, I thought that you would have worked with modbus previously... MODBUS is only a software spec that defines the protocol and that works on 232 or 485. So this is another story...

In order to get it working using Beckhoff, for instance you should get a CANOpen card. Once you've got that card, then buy and install TWinCAT, after that you'll be able to configure the card using system manager. You will be able to decide what to do: Using TWinCAT PLC Control to create a PLC program inside your PC or using the ADS to communicate with a VC++ application if you want...

The software based CNC/PLC systems out there work using separated layers:

[Physical layer - Electronic cards] - connect the pc to the physical world.
[Configuration layer - System manager] - configure / set up the electronics.
[PLC layer - TWinCAT PLC Control] - up to 4 software logics (virtual PLCs).
[CNC layer - TWinCAT CNC / NCi / PTP] - up to 256 axis controlled in different ways.
[ADS layer - Windows application interface] - the way you will be able to get information into your windows apps.

In order to get ADS you need to install TWinCAT and it is not free... a PLC license should be enough, or possibly a CONTROL PANEL license (I'm not sure about that).

The problem here is the concept change:

When you worked in MODBUS you did not needed an external help. The physical layer is already installed into the PC and therefore no extre material is needed, only software.

Here you'll need electronics and therefore you'll need the propietary software from the manufacturer to be able to interact with them.

So you'll have your physical world connected to the PC using electronic cards and some software that will act as a master/slave in the CANOpen bus.

Check the links I sent you... I don't think so, but it is possible that inside the first link you could find something cheaper.

Good luck!

PS: CANOpen is not precisely the easiest field bus in the world... as it's name suggests it's really open, and this will give you more than one headache... it is powerful but way too complicated, it is easy to implement in electronic terms... and this is why electronic manufacturers still go there (slower CPU's to get the bus working...) but it lacks of several modern busses capabilities...