EDNE January 2013 - (Page 18)

Viewable on iPad/iPhone EW ! N READ INDUSTRIAL AUTOMATION NEWS MAGAZINE GET ESSENTIAL INFORMATION ABOUT AUTOMATION SECTOR 100% DIGITAL TU RN M AY 2 0 1 2 I N D U S T R I A L A U T O M AT I O N N E W S - W W W. I A N M A G . E U Page 6 Siemens has expanded its Simocode pro motor management system with a Profinet interface, linking up Simocode pro via Ethernet to higher-level automation systems to allow new functions to be provided for motor diagnostics. ISaGRAF issues a major release, version 6.1, of the software design environment for building industrial automation products, compliant to international standards IEC 61131-3 and IEC 61499, and built on Microsoft Visual Studio 2010. Page 8 ROBOTIC ASSEMBLY CHANGES PRODUCTION ECONOMICS Fast automated assembly removes need to take manufacturing offshore; Page 12 The test board in Figure 1 uses eight ports connected to four individual, single-ended transmission lines, as differential channels. There are only four ports and two differential pairs. Applying the labeling scheme used for the single-ended ports, the differential ports would be assigned as diff port 1 to diff port 2 and diff port 3 connected to diff port 4. As part of the accepted formalism of differential or mixed mode S-parameters, the letters D and C designate differential signals or common signals respectively. Any combination of a type of signal entering a diff port and a type of signal coming out a diff port are identified by the coming out letter, the going in letter, the coming out port and the going in port. For example: SDD31 is the near end crosstalk for differential to differential signals SDD41 is the far end crosstalk for differential to differential signals SCC31 is the near end crosstalk for common to common signals SCC41 is the far end crosstalk for common to common signals SCD31 is the crosstalk of a differential signal as the aggressor, converting to near end common signal The channel-to-channel differential and common crosstalk are shown in Figure 5. This clearly shows the advantage of tightly coupled differential pairs to reduce channel-tochannel crosstalk. The differential signal near and far end crosstalk is more than 20 dB lower than the common near and far end crosstalk. This graphically illustrates why differential signaling can sometimes decrease crosstalk between channels over common signals or single-ended signals. Crosstalk between high speed signals is complicated. It depends on which end of the aggressor line the signal enters and on which end of the victim line you look. It varies with frequency in a complex way and may vary with rise time. The S-parameter formalism is a natural way of characterizing this complex behavior. Each matrix element describes the crosstalk between any pair of ports displayed in the time or frequency domains. They can be measured with a network analyzer or simulated with many popular circuit or electromagnetic simulators. If crosstalk is an important problem in your designs, it may be time to embrace S-parameters. T&MW RefeRences Bogatin, Eric and Blankman, Alan. “Avoid a common S-parameter problem: How you assign ports can greatly affect measurement interpretation”, Test & Measurement World, April 25, 2012. 2 Bogatin, Eric. Signal and Power Integrity – Simplified. Upper Saddle River, NJ: Prentice Hall, 2010. 3 “Measuring NEXT and FEXT Crosstalk with LeCroy SPARQ Signal Integrity Network Analyzers,” LeCroy Corp. 4 “LeCroy SPARQ Signal Integrity Network Analyzers” LeCroy Corp., 2012 1 Agilent Technologies has introduced a Bluetooth module for its hand-held digital multimeters; a “mobile meter” application enables remote readings and data logging on on the screen of any Android-based smartphone. Page 22 FREE OF CHARGE AT www.ianmag.eu/subscription 18 EDN EUROPE | january 2013 SUBSCRIBE NOW Eric Bogatin is a signal-integrity evangelist at Bogatin Enterprises (a LeCroy Company) and Alan Blankman is technical product manager for signal integrity at LeCroy, www.lecroy.com www.edn-europe.com http://www.ianmag.eu/subscription http://www.IANMAG.EU http://www.lecroy.com http://www.edn-europe.com

Table of Contents for the Digital Edition of EDNE January 2013

Digi-Key
Cover
Contents
Agilent Technologies
Microchip
Embedded World 2013
Masthead
EDN.comment
Digi-Key
Pulse
Analog Devices
Use S-parameters to describe crosstalk
Rohde & Schwarz
IAN
Designing low-energy embedded systems from silicon to software
Baker’s Best
Analog Devices
Analog Devices
Conditioning techniques for real-world sensors
Design Ideas
Mechatronics in Design
Product roundup
Tales from the Cube

EDNE January 2013