I read with high interest your cover story in the January 1998 issue of Control Engineering ["Connect to the Benefits of Digital Industrial Networks," p. 48]. I was surprised you didn't mention the CAN in Automation (CiA) International Users and Manufacturers Group, the most successful fieldbus club. Perhaps we are too independent—covering all the CAN-based solutions.

ODVA and Honeywell are CiA members—CiA is the umbrella organization for all CAN users. Last year, there were about 30 million CAN nodes sold, which is more than all the other bus systems together sold in their whole lifetimes.

CiA has developed the CANopen profile family, which can be regarded as a competitor to DeviceNet and Smart Distributed Systems. Nevertheless, we promote all of them because it is not the task of a user club to decide which is the best higher-layer protocol for CAN. In the U.S. and Japan, DeviceNet is better established than CANopen. In Europe, CANopen is more accepted, especially in the openOEM businesses and other control application fields, such as off-road vehicles, medical electronics, etc.

Holger Zeltwanger, CiA managing director, CAN in Automation International Users and Manufacturers Group, Erlangen, Germany.