This is going to be a tough one. Softing and Hilscher would be my usual suspects for this.
Are you talking about the H1 Foundation Fieldbus (the two-wire implementation) or the higher level HSE Ethernet-based network ?
What CAN-based network protocol are you using ? CANOpen, or something different ?
My experience with Foundation Fieldbus has been entirely in multi-vendor applications, and I have a very negative opinion of the technology. I'm sure it's a lot easier to use if you're using a major vendor DCS and that vendor's instruments.