Keeping the old bus going

Recalling a presentation from an end user conference more than a decade ago, Juan surmised, “Some folks just want to drive the car.” The revelation came from a pharmaceutical company faced with maintaining the supplier’s distributed control system (DCS) around the world.

Like a motor vehicle, some end users just want to hop in and use it for its intended purpose—to get from point A to point B. In Juan’s world, the culture of tinkering, tuning or “puttering around” with one’s automobile seemed to be vanishing.

Likewise, there’s a segment of instrument and controls (I&C) professionals who are curious about settings, filtering, tuning, etc., often out of necessity. If the tech configures a first-order filter in the transmitter, a second one in the I/O, and another in the PID block, the efficacy and stability of the ultimate control loop might be adversely affected. One wonders, is “just drive the car” achievable when joining disparate devices, each configured in its own silo, or not configured at all?

Juan remembered the befuddled turbomachinery specialist, who struggled to reconcile his horsepower curves with the measured admission and extraction steam flows. It seemed like years before someone noticed there was a square root applied to a vortex flowmeter’s analog input block. Whoever configured the blockware in the early going must have assumed they were connecting a differential pressure flowmeter. Could Juan provide his successors with sufficient guidance or procedures to ensure all important parameters were scrutinized?

More than a decade ago, NAMUR, an international user association for automation technology in the process industries, published recommendations (NE131) which were woven into FieldComm Group’s Process Automation Device Information Model (PA-DIM), which aims to better standardize and focus on the essential parameters end users must scrutinize to obtain a useful measurement. Some manufacturers develop methods or wizards, which automate many aspects of device configuration but still require mindful input from the user. Both technologies rely on platforms like Electronic Device Description (EDD), once the bane of early fieldbus adopters which has now been visited upon HART and WirelessHART. Also, one might download a device type manager (DTM) or a field device integration package, which aims to support all the best aspects of EDD. 

Get your subscription to Control's tri-weekly newsletter.

Juan was struggling to turn off the analog output block of a positioner he wanted to use in discrete (on-off) mode, but even the DTM didn’t afford the options he needed. He was going deep in the weeds and worried whether his technicians would even know where to start. He also noted how massive the DTM downloads were. Even his relatively state-of-the-art field communicator required periodic updates, which—unsurprisingly—were available with a subscription. The tinkerer could figure out how to load DDs on the Trex without a subscription, but all Juan could envision was the frustration of the less adventurous when a device wouldn’t connect.

What about AI? Microsoft’s CoPilot had given him the idea to disable the analog output block in his fieldbus positioner, so he could get the discrete blocks to function—the parameter tweak he couldn’t get to work. When prompting CoPilot to set up his flowmeter, the advice was detailed and verbose, and useful. While he already knew most of the answers in advance—how to set the channel, transducer scale, linearization type—CoPilot also highlighted nuances about filtering/signal conditioning that were new to him. He was pleasantly surprised that engineers at his suppliers were working to bake-in features that defied the commoditization of field devices, but Juan needed AI to find them.

I&C professionals can choose to delve deeper into the measurement and control system, taking advantage of advanced features and diagnostics. Juan didn’t realize his mag meter could also provide conductivity, or that his vortex meter could report temperature. Once configured, those who follow will still need to understand where to find these capabilities and how to tune a similar or replacement installation.

The day may soon come when Juan’s Bluetooth-connected device interfaces directly with cloud-based AI to guide configuration. Whether that technology will help extend the life of legacy fieldbus systems remains uncertain. Knowledgeable practitioners motivated to delve under the hood will be essential for decades to come.