CAN/CANopen® FAQ

Q: When and why would I need a higher-layer protocol such as CANopen® instead of plain CAN?

A: CAN by itself only provides a method of exchanging up to 8 data bytes using message frames that have an identifier. Once you sit down and specify which identifier is used for which purpose - and what the contents of each message means (data types, byte order, variables) you are already starting to specify your own higher-layer protocol.

As soon as a certain number of nodes, messages and network variables are involved, an in-house specification of that higher-layer protocol needs to be written and maintained.

With CANopen® all of that work has already been done. Instead of re-inventing existing technology, engineers can take advantage of CANopen® and adopt existing technology.

Due to the "openness" of CANopen®, it is even possible to pick and select the features required by an application and skip the unwanted ones. CANopen® literally reduces an in-house specification to a document that states which features of CANopen® are used.

Most commercial CANopen® source codes support the selection of features via "#define" statements in the source code.

If you are not yet certain if you want to use CANopen® or implement an in-house higher-layer protocol, consider using www.MicroMessaging.com or www.MicroCANopen.com instead.

Do you have more questions or comments on our answers?

Submit them to: info@canopen.us