The old practice of adding IO tiebacks and simulation into the control system configuration is still being promoted by some companies in the automation industry. It’s a bad direction for a process company to take and here is why.
Munger Company, a St. Louis based automation company, had a problem on automation projects startups. Their engineers had no real way to test the control system configuration well before startup and mistakes and design errors in process control were killing them on plant startups. They tried adding IO simulation to the control system configuration but that only added additional errors when they removed the IO simulation before delivery to the plant. On top of this problem, the plant managers wanted to train operators before startup and there was no real way to build even simple process models. Rick Story (VP of Munger Company at the time) came up with the idea of an IO and process simulation system that was external and non-intrusive to the control system. He recruited a young software engineer named Nobin William (now MYNAH VP of Technology) to develop a product named SIMVOX. Using SIMVOX, project performance and customer satisfaction changed overnight. Control system configuration quality improved and they even had a solution for building process models for operator training.
SIMVOX was a breakthrough technology in its time. It ran under Digital Equipment Company’s VMS operating system, required the user to build models in Fortran files, and was, by today’s software standards, primitive, but it was better than the flawed practice of adding IO and process simulation into the control system. Yet this same flawed practice is still being used and even promoted under the name of a “native” simulation offering.
It is incredulous that this approach is even considered with the current tools available for dynamic simulation of automation systems. Almost every automation company had a control system simulation or emulation offering that allows the user to run control strategies, operator graphics, and complete configuration in a PC environment unchanged. These control system simulators have open interfaces using OPC, Modbus TCP/IP, or EtherNet/IP for IO stimulation and training snapshot and speedup/slowdown controls. They are built to be used with a non-intrusive, external IO and process simulator. The integration of these two systems using open protocols is a trivial task.
In spite of the advances in product offerings and technology, some users and solutions providers still try to convince process users to add simulation to their control systems. This flawed approach should be avoided for the following reasons:
Instead of adding IO and process simulation to the control system configuration, consider the virtual plant. The Virtual Plant uses the automation company’s control system emulator with a dynamic IO and process simulator. It overcomes the issue with “native” DCS simulator deployments while providing a proven infrastructure for operator training and control system optimization and testing. The value of this approach to process plant operators is explained in the Business Case for the Virtual Plant Using Mimic Simulation Software.
I look forward to your comments, questions, or suggestions.
Hope to hear from you soon.
Mart Berutti, 03/23/12
MYNAH Technologies LLC
390 South Woods Mill Road, Suite 100
Chesterfield, MO 63017 USA
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