Process Control System Upgrade



Business Issue

It was determined during the last process control system upgrade that advanced diagnostic information from plant process instrumentation was required. Some of the plant instrumentation assets were classified as critical and plant management desired on-line diagnostic information to allow for the most effective operation and maintenance decision making. The existing DCS did not support this functionality or the throughput of this information but could provide an instrument connection point to the field devices. An AMS Suite: Intelligent Device Manager system was installed to allow for access to process instrumentation diagnostic information. With thousands of instruments in the field and a declining number of Instrument Technicians available to maintain the plant equipment, an increase in on-line diagnostic information would allow maintenance personnel to be more efficient in troubleshooting and correcting process issues.

A recent situation at the refinery reinforced the vision of needed on-line diagnostic information. The refinery was faced with troubleshooting a control loop during an unplanned major process unit shutdown. The failure had to be corrected in order to bring the process back online as soon as possible.  A faulty positioner was the preliminary diagnosis. The shutdown occurred late at night after a process feed control valve failed to the closed position. Refinery instrumentation technicians responded to the outage. The first indication of the process problem was a DCS system status alarm. The DCS had been configured to continuously monitor the output wiring to the valves and the alarm indicated an open wire or bad connection in the circuit. 

After performing diagnostic checks utilizing Emerson Process Management’s AMS Device Manager it was quickly determined that the valve and positioner were functioning properly and no more time should be dedicated to troubleshooting the control valve assembly. Time was critical and the technicians were now able to move on to troubleshooting in other areas. The technicians found wiring in the junction box that was not terminated properly. They repaired the wiring and the immediate issue was resolved. The Operations personnel then proceeded with the unit startup.

Project Summary

An on-line, distributed AMS Suite: Intelligent Device Manager system was installed during the process control system upgrade. 46 HART Multiplexers were connected to existing DCS Field Termination Assemblies (FTA) without disturbing the existing field wiring. The Multiplexer network was connected to two server stations that allow local access to the connected devices as well as provide plant control LAN access for use with client laptops. A client laptop was located in the Instrumentation Maintenance Planner’s office to allow for real time evaluation of devices and monitoring of suspect or intermittent devices through Alert Monitor functionality.

Scope Responsibility

Cornerstone Controls has been involved in the following aspects of the system:

  • Design and commissioning of an on-line AMS Suite: Intelligent Device Manager system including server stations, client stations and associated Multiplexer Networks.
  • Configuration of Alert Monitor for automatic interrogation of devices.
  • Provided training for the Instrument Technicians and Planner on specific AMS Device Manager functionality, as they pertain to different instrument types. This training included control valve Advanced Diagnostic Testing using the AMS ValveLink Snap-on and Fisher DVC positioner.
  • Provided system upgrades as new functionality was released, and refreshed customer training as applicable.


The following savings have been realized through the implementation of the AMS Suite: Intelligent Device Manager system:

  • Improved efficiency during process troubleshooting due to plant-wide access to instrumentation asset’s diagnostic data.
  • Increased reliability and improved dynamic response of control valve assemblies.
  • More effective maintenance budget allocation and time requirements for instrument and control valve repairs by eliminating un-needed preventative maintenance (PM) actions and performing repairs based on predictive maintenance (PdM) strategies.