One of the hardest parts of EMC immunity testing is monitoring EUT (Equipment Under Test) performance. Not that it is hard-as-in-complicated but it is hard-as-in-difficult.
Concentrating on a display of figures scrolling past looking for small deviations in one or two characters sounds easy, but try doing it for a couple of hours straight whilst doing Radiated RF Immunity testing and you will be fighting an itch to defocus, stare off into the distance or check the news on your phone.
Go on, ask me how I know 😉
Not ideal when you only have a short (think a few seconds) window to catch potential problems or if you have multiple screens to monitor.
Introducing the Monitor-o-Matic 8000
To remedy this and improve the quality of our testing we’ve written a simple application in LabView to handle logging and display of data captured from the EUT during testing.
- COM Serial input to monitoring PC from EUT. all standard serial port baud rates and configurations supported
- Use USB to RS-232 or RS-485 adaptors to connect serial port to EUT
- Extract values / parameters from data stream
- Plot numeric values on graph
- Record min and max values seen during test to determine if EUT meets appropriate performance categories
- Logging of all data during test (all data will be made available as part of any immunity testing carried out at U3C for post testing analysis)
- Alerts/alarms for data that exceeds defined performance limits. These can be set to latch on in case of problems to prevent missed alarms
1) EUT has the ability to output serial debug ASCII text data for all key parameters like
- analogue sensors (e.g. temperature, pressure, humidity, light, voltage, current, etc)
- digital I/O values (e.g. High/Low, True/False)or system status
- raw digital values read from other parts of EUT
- checksums from memory
- whatever other parameters that you need to monitor to ensure the EUT is working as intended during the tests
2) Format could be human readable text, comma delimited, JSON, XML… whatever gets the job done for you. So long as the values are extractable from the text using regular expressions we can log and plot the data.
3) These can either be output as a continuous stream of data that the MoM8000 software will parse, or the EUT could require separate commands to read each parameter. If you can send us an example serial output ahead of time we can get the software setup before your arrival so that no testing time is wasted during setup.
4) We also need to know what performance limits you might have (e.g. temperature deviation of +/- 0.5C) so that we can enter the appropriate limits. This notification is key as it lets us quickly evaluate EUT performance to the Immunity Criteria (A/B/C) in the appropriate standard.
We’ll be adding extra functionality to this software over time when we develop new requirements. This includes:
- Subscribe to MQTT topics on local or remote server
- Read HTTP data
- Read text data file on local network
- Tighter integration of test equipment and software to speed up EMC tests
Discuss with us in advance if you have a special requirement for testing and we will do our best to accommodate you.