Just like we tend to take the Ethernet chipset in our computer for granted, most End Users are likely unaware that every Foundation Fieldbus H1 device has a similar chipset called the H1 Stack in it. Like the FF Function Blocks, the stack must also be tested for compliance BEFORE the device can be submitted to the Fieldbus Foundation for its 'check mark.' Because the Foundation now tests devices and host systems, every field device and H1 interface card therefore requires a tested and approved stack. Testing of the stack for compliance with the FF standards is done at the Fraunhofer Institute in Germany http://www.fraunhofer.de/en/.html.
Development and maintenance of an H1 stack is not a trivial process and need not be done very often many manufacturers outsource this component to a third party. Many of the large manufacturers such as Yokogawa and Emerson use their own stack but the majority of manufacturers simply purchase a stack from someone else. The two most common sources for folks not using their H1 stack are Smar http://www.smar.com/en/ in Brazil and Softing http://www.softing-ia.de/en/industrial-automation/ in Munich, Germany.
I recently learned that Softing presently provides the H1 stack in 60% of field devices and 70% of Host systems on the market. This does not mean that is how many total devices use their chips but rather of the several hundred FF devices with a check mark the majority of them are based on the Softing stack so effectively they are the Broadcom of H1 communications.
Marketing people suggest that if you have >80% of the market you are close to a monopoly position and since Softing is almost in there the implication is that they carry significant weight when it comes to defining the H1 Physical Layer communications or any changes that might be required.