The new HART solution allows the safety system to access the HART parameters. This enables operators to use device diagnostic information (e.g., about potential failures, upcoming failures) inside the safety instrumented function (SIF) logic. Although this information is not safety related, it can be used inside the SIF logic as an independent, additional layer of protection. Gas sensors, for example, can notify via HART that they will fail in the near future, giving plant personnel the chance to react in advance (predictive maintenance).
The HART solution contributes to increased plant safety by allowing the system to monitor configuration changes – even if made via handheld devices. This information can be used to modify logic, to bypass disabled devices, or to initiate a shutdown.
Furthermore, proof tests such as partial stroke tests for valves can be initiated and managed from the safety system. With existing HART solutions, it is possible for personnel (or external hackers) to reconfigure the field devices via the Asset Management System. This poses a major cybersecurity and safety risk.
If, for example, a limit value of a SIF (safety integrated function) is set to 75% of a measuring range of 10 bar, and someone changes only that range within the sensor to 100 bar, the ESD is triggered only when the level of 75 bar is reached – meaning the SIF will fail to do its job, causing major safety and production problems.
HIMA’s HART solution closes this security and safety gap in today’s process industry. By channeling communication through a safety PLC featuring enhanced security—instead of through a separate HART multiplexer or by standard tunneling as is currently the norm—the communication benefits from the additional firewall. The firewall allows data reading but prevents data writing/configuration and the direct access to field devices from the Asset Management System.
Buddy Creef, Sales Director HIMA Americas, says, “We realize that there is significant value that can be derived from the use of HART data to make the SIF more reliable, but we also know that HART creates some vulnerability. With this new solution, which is the only one on the market offering TÜV-certified write protection and HART filtering in SIL 3 quality, we allow plant operators to have their cake and eat it, too”.