ISO/IEC Standard 17025:2005 – General Requirements for the Competence of Testing and Calibration Laboratories addresses Software Validation in Clause 220.127.116.11.
Clause 18.104.22.168 says the following:
When computers or automated equipment are used for the acquisition, processing, recording, reporting, storage or retrieval of test or calibration data, the laboratory shall ensure that:
a) Computer software developed by the user is documented in sufficient detail and is suitably validated as being adequate for use;
b) Procedures are established and implemented for protecting the data; such procedures shall include, but not be limited to, integrity and confidentiality of data entry or collection, data storage, data transmission and data processing;
c) Computers and automated equipment are maintained to ensure proper functioning and are provided with the environmental and operating conditions necessary to maintain the integrity of test and calibration data.
NOTE: Commercial off-the-shelf software (e.g., word processing, database, and statistical programs) in general use within their designed application range may be considered to be sufficiently validated. However, laboratory software configuration/modifications should be validated as in 22.214.171.124, item a.
Most EMC software developed by EMC equipment vendors are considered to be lab software configurations and should be validated as in 126.96.36.199, item a. This is also true of software developed internal to the EMC lab for its use.
Validation usually consists of manually checking frequency and amplitude for emissions being measured to assure that the manual-check answer and the software answer are the same.
The validation is similar for immunity testing; if the software says it is generating 3 volts per meter in a radiated immunity test then the manual-check with an electromagnetic field sensor should also indicate that the field is at 3 volts per meter.
In rare instances, an EMC Lab may have two software programs for the same measurement process; in that case, the lab can validate the numbers from program #1 by running program #2.
Software programs for measuring electromagnetic emissions and for controlling electromagnetic immunity-test hardware for subjecting equipment-under-test to both radiated and conducted stresses have enabled EMC labs to test products more efficiently and in a more consistent manner. The danger in the software programs comes from assuming that they are operating correctly in every possible scenario. Software validation is the engineer’s way of assuring that the software is doing what is programmed to do.
|Daniel D. Hoolihan
is the Founder and Principal of Hoolihan EMC Consulting. He is a Past-President of the EMC Society of the IEEE and is presently serving on the Board of Directors. He is presently an assessor for the NIST NVLAP EMC and Telecom Lab Accreditation program. Also, he is the Vice-Chair of the ANSI ASC C63® committee on EMC.