One of the most common direct coupled noise sources is when the ground which is being used for reference or return is not referenced to earth as expected. This is especially prevalent in sensitive high-gain circuits. Grounding and Shielding Existing Equipment – How to effectively minimize EMI issues when best practices are not available is →
Grounding and shielding is an often misunderstood process. It is common to hear quotes ranging from “it’s just black art!” to “the rules change all the time!” and “there’s no way to understand it!” These statements are often repeated but not true. There is a process, it hasn’t changed, and the more one knows about →
How to protect RS-232 serial connections article pointed me to a recent white paper from APC-Schneider Electric that explains specific power protection issues related to RS-232 cabling. The Protection of RS-232 Serial Connections document contends that the RS-232 port often represents the “Achilles heel” of computer installations which are otherwise well protected by UPS systems →
OpenPLC, for industrial automation to Halloween displays article factories have programmable logic controllers to take care of their automation tasks and they are also good devices to control your Halloween effects. open-plc project is an open hardware design to build your own programmable logic controller. Included in the OpenPLC are four 24V inputs, four 24V →
There are some common rules in the design of user interfaces (UI) in embedded systems, such as, “use common dialogs and buttons familiar to your users” or “keep it simple by limiting user activity, as much as possible, within the context of the current function”. The design of these buttons, dialog boxes, help screens and →
John Huntington’s Entertainment Technology Site blog has an interesting article series on using Ethernet on show control applications. The articles concentrate on Gravesend Inn haunted attraction, that is a pretty good reflection of the progress of networking technology in the field of entertainment control. Back in 1999, was built around around hard wired sensors/closures and →
SCADA systems are used to monitor and control critical installations in oil and gas refineries, water and power distribution plants, manufacturing plants and other industrial facilities. There has been a lot of discussion about malware and security in industrial automation systems after Stuxnet. Widely viewed as the most complex piece of computer malware ever created, →
EMC Basics #5: I/O as critical circuits article gives some useful tips on the EMC issues related to inputs and outputs. Digital inputs/outputs — The key concern for digital interfaces is ESD. A secondary concern is radiated emissions. Radiated susceptibility is rare with digital I/O, although possible at very high RF levels. The solutions for →
Proper grounding is an essential component for safely and reliably operating electrical systems. Improper grounding methodology has the potential to bring disastrous results from both an operational as well as a safety standpoint. There are many different categories and types of grounding principles. Proper Grounding of Instrument and Control Systems in Hazardous Locations paper’s primary →
Troubleshooting grounding problems can be difficult at best. Especially on complex automation/instrumentation systems. Use your power system drawing or a system map to document as you go because these problems can be quite complex requiring some logic to figure out. The typical utility DC bus consists of a battery charger, a string of batteries, a →