Letter Re: Some Notes About SCADA Software


The pastor/programmer is somewhat correct about SCADA and Programmable Logic Controllers (PLCs), and his resistance of Windows based and “soft logic” is admirable. However, many SCADA systems installed out there recently have been implemented just as their name implies “SUPERVISORY CONTROL and Data Acquisition” in order to save labor costs by minimizing operator and maintenance training requirements on multiple different in- plant control systems. Most major power, refining, waste treatment systems etc. in recent years have utilized a DCS (distributed control system) as a SCADA base for overall and/or supervisory control often also monitoring or commanding smaller PLC systems operating auxiliary systems ( compressors, large blowers etc.). And although “manual back-up” is often available on “critical” functions it typically is limited to safety shut down and control transfers, not operation maintainability. Almost all major control systems built in the past 30 years are DDC (direct digital control) DCS, PLC, electric analog, or some type of microprocessor based controls. Even if the controls are old pneumatic analog they rely on compressed air controlled by a PLC. This basically makes almost all major plant control systems out there vulnerable to EMP effects. And although some of the hardware utilized may have been specified with EMI (electro magnetic interference) and RFI (radio frequency interference), this typically will only help with 5 watt communication radios and 220 or 440 power interferences. Certainly nothing as devastating as a large nuclear EMP blast as described in the novel “One Second After” or even a large solar flare.

I’d suggest the pastor, and many others, read the 2008 Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack. It speaks in great lengths of the susceptibility to damage of various types of plant control systems in a wealth of industrial applications.

Hopefully none of this will ever become a problem, but the pastor is wise to follow your advice to prepare. “Plan for the worst, hope for the best” – G.S. (A Senior Control Systems Engineer with 40 years of experience in SCADA)