The best way to judge the openness of a communication protocol is by the number of products supported.
By this standard, the HART protocol is perhaps the most open of any field-communication protocol available today.
In a major refinery expansion, an oil company weighed the advantages of using either a proprietary system or a HART-based system. The results indicated that the company could use HART digital instruments in 92%
of their applications, compared to only 33% with the proprietary system.
Choosing HART products resulted in an incremental $23,000 in savings due to commissioning efficiencies and ongoing maintenance and diagnostic capabilities.
The oil company used a traditional control system with analog I/O and supplemented the control capability with an online maintenance and monitoring system. All of the HART field devices were monitored from a central location (Figure 26).
Figure 26: Online Implementation
