By John Rezabek, contributing Editor
Digital integration of field deviceswhether through proprietary protocols, HART or fieldbuscan provide an opportunity for significant business results, but only if key players know where to find the data and what to do with the information. Cryptic messages, alarms or diagnostics that have to wait for Bubba to show up on Monday can put a crimp in your efforts to harvest the benefits of device intelligence.
Our plant just underwent a brief swoop-down, during which a flowmeter with plugged impulse line detection went into alarm. The device in question has an option to affect signal status, which transmits an uncertain statusspecifically, uncertain subnormal along with the DP measurement, when the diagnostic is invoked.
I didnt see the message until a few days later. It was a false positive generated because the line in question was blocked inand an example of data not being equal to information.
Operatorsthe pilots of our process plants have an interest in the validity of measurements. In the case of plugged lines, they can understand the alarm and its consequences, and can take action more-or-less immediately. Why cant I get them this information in a way thats more meaningful?
A clever graphics designer who happens to know the specific integer value of Uncertain Subnormal perhaps will have the time to customize the graphics to display plugged line detected instead. But by the time that designer comes along, you could be years into your fieldbus, with a half-dozen installations behind you that could have benefited and a repertoire of standardized graphics and modules that are difficult and expensive to change.
The Emerson DeltaV system uses a capability called Plantweb Alerts. With post-2004 versions of Emerson software, you can enable devices to send device alarms directly to the system. The problem has been, unless you had Emerson devices of recent vintage as well, everyone got all the alarms generated by devices, regardless of priority.
If you happen to have the latest Rosemount transmitters or Fisher positioners, these have the added capability to route specific alerts to either maintenance or operations. This feature gets very close to solving this issue for users: A few mouse clicks can potentially get that message to the right person at the right time.
In our case, we focus on instruments in critical services and expand from there. Sometimes, the diagnostic you think is meaningful to your operations organization isnt available as an alert that can be routed to the person who can use it. For instance, the plugged line diagnostic is categorized as maintenance; at the moment there is no option to elevate it to operations. So Im back to creative graphicsif I dont want to wait until Monday morning when, we hope, Bubba finally looks at the PAMS alerts. If a plugged line has the potential to impact your process more-or-less immediately, this is not an acceptable option.
But there is good news. Emerson has announced that the technology for Plantweb alerts will be released as an open standard. Not long after, Fieldbus Foundation is releasing a new standard, based on NAMUR NE-107, that addresses this very issue.
Similar to Plantweb alerts, the standard calls for devices and the host systems to support four levels of alarms/alerts for field devices. Once integrated into products, an end user will be able to classify each device alert/alarm/diagnostic as critical (failed), maintenance, advisory or a fourth category: device being servicedwhat Herman Storey calls Bubbas workin on it. Users will have the capability to route each alert according to their individual preferences.
In the battle to distill useful and timely information from the tsunami of data available in smart devices, having this capability in brand-agnostic formwill be a huge benefit. Be sure your favorite suppliers are getting ready to deliver it.