[SOLVED] Measuring Switching Points or Switching Transitions

What kinds of circuits would you want to measure the switching points or switching transitions of logic signals or comparators?

I have measured on a 4 channel O-scope, each channel is measuring a relay contact or a switch contact

What circuits have you guys do this for?

To measure multiple relay contacts or switch contacts

A relay or switch contact simply turns something on and off doesn't it? A relay switches slowly and its and a switch's contacts bounce. Then why use a 'scope? Use a voltmeter instead.

Because I would need to use 4 DVM meters on 4 different switches or relays to see which contact has an intermittent problem

I use a 4 channel storage O-scope to view 4 channels of switches or relays opening and closing and look at the switching transition

One relay coil can have multiple switches, when energizing the relay coils it can open or close multiple contacts. That's why I use a multi channel O-scope to view the opening and closing transitions of multiple contacts or switches

How would you troubleshoot a switching failure like this?

Hi colleagues!

Sorry, but I still do not fully understand your task. You need sometimes to check the chain of contacts in case of failure scheme, or if you want to make a built-in automatic detection of failures relay circuit?

If you want to determine the cause of the rare hardware failure, then you need to use measuring tools. As one of the options - the oscilloscope. But to measure the logic levels also exist logic analyzers. They exist in the form of an attachment to a computer, they have a plurality of inputs, considerably cheaper oscilloscopes! But require a computer. And there are also standalone logic analyzers, with a screen like the oscilloscope. In any case, you should pay attention to the maximum sampling rate of the logic analyzer that he was able to keep track of short pulses bounce relay (if you need it).

If you want to make an autonomous control system enable relay contacts and determine their failure, it is necessary to make the scheme on the basis of the comparators, sensor short pulses (if you want to discover the contact bounce) or microcontroller. In this scheme must be laid down on the normal verification algorithm of the your relay circuit. And if the algorithm does not correspond to the normal algorithm of the relay circuit, then this additional circuit will supply an alarm (LED indicator or beep sygnal). In this case, the project will be individual.