Firewall Needed Between AT and IT?



Lynn W. Craig

A: In our company, it is the controls group that takes care of the DCS, but the regulatory responsibility is not clearly defined. It is logical to have the control group be responsible for DCS, as it is connected to field instrumentation. Also P&IDs, cause and effects need to be built in DCS. Also, the instrument engineers are knowledgeable about measurement and control. In my view the same separation should continue.

H. S. Gambhir

A: In the beginning (1970s), this question did not exist since microprocessor-based and computer-based process control systems were not common. PID control loops and hard-wired and electrical relays were used. In 1980s, microprocessor-based control systems began to be common, while in 1990s DeltaV and other PLC control systems entered process control.

Instrument engineers did not consider DeltaVs computers, but IT people treated them as software, since control logic, configuration, etc. were used to make the device (DeltaV) work. Other computer-controlled systems, such as vibration monitors, anti-surge control for compressors, etc., were added in the heated debate between instrument engineers and IT people. IT people tended to view the whole picture as a function of Internet security, software validation, system integrity, etc., and often had been authorized to approve the system before a computer installation was to be procured.

In 2000s, model-based control, system identification, statistical analysis, SIS, etc. became popular, and IT people became more aggressive in taking control of the approval process. During an emergency or when a process was down because control signal failure, loss of measurement signals, valve failures, etc., instrument engineers were sent to fix the problem. When the office computers were down due to hacking, viruses, software compatibility, etc., IT people were sent to fix the problem.

I am not qualified to judge what IT people know. However, anyone who wishes to decide what instrument engineers should use in process control had better be equipped with the ever-evolving knowledge in instrumentation.

Gerald Liu

A: Emerson—as all DCS vendors—takes great care in testing DeltaV as a system with each software update. This includes the software for the HMI that happens to run on a Windows platform. If your IT department were to install any updates, there is a distinct possibility that those updates may break some DeltaV function. You will not be covered for any DeltaV system malfunction resulting from using a Windows version different than that supported by the DeltaV version you have installed. I believe that Emerson does offer a service contract that includes updating Windows software, but only after they have validated that it does not affect any DeltaV functionality.

Allowing your IT department to update Windows on your HMI or engineering workstations is a bad idea. We always tell our end-user clients to tell IT that the HMI and engineering stations are parts of a manufacturing machine and are not computers.

Richard H. Caro,

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