How to estimate Maximum speed of the meter and what is 1NPLC setting

Thread Starter

Note Theeraphan

Joined Jan 15, 2018
21
Hi All,
now, I'm studying regarding minimum time or maximum speed of the meter
I need to use 1Meter to measure resistance of 20DUT (device under test) by using Multiplexer switch to each DUT
and I need least test time to measure resistance all of these DUT, So I have to know the minimum time that meter can measure

as study, I found the word about NPLC setting and I not sure whether my understanding as below is correct or not?
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1 NPLC or 1PLC = 1 Power Line Cycle
so the Power Line Cycle is AC line frequency = 50Hz = 20mS
thus, 1PLC = 20ms
so I have to on multiplexer at least 20ms / DUT

Correct???
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please let me know if you have suggestion or other solution
thank!!!!!
 

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Picbuster

Joined Dec 2, 2013
998
how long is a rope??
we need more info
what is 1Meter measure resistance ?? (air, metal, glass, water,petrol or ????)
What to test?
How to test?
Time needed to do the test?
Why 20ms? Why not 1 micro second, one hour or a day?

Please provide information if you want answer(s).

Picbuster
 

Thread Starter

Note Theeraphan

Joined Jan 15, 2018
21
how long is a rope??
we need more info
what is 1Meter measure resistance ?? (air, metal, glass, water,petrol or ????)
What to test?
How to test?
Time needed to do the test?
Why 20ms? Why not 1 micro second, one hour or a day?

Please provide information if you want answer(s).

Picbuster
Hi Picbuster
sorry for unclear question

how long is a rope??
ans: it it PCB trace length about 100mm

what is 1Meter measure resistance ?? (air, metal, glass, water,petrol or ????)
ans: resistors+PCB trace / equivalent resistor in circuit

What to test?
ans: To check resistance is in spec or not

How to test?
ans: please see as diagram or attached files
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[/IMG]

I need to know minimum time "ON" that Meter can measure resistance of each resistor


Time needed to do the test?
ans: I need least cycle time for 20resistors, now I don't know how to calculate


Why 20ms? Why not 1 micro second, one hour or a day?
ans: I don't know, how about 1PLC, it it 20ms?

thanks!!
 

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Last edited:

AlbertHall

Joined Jun 4, 2014
9,826
The meter manual will tell you the sample time. You also need to consider the time it takes to command the multiplexer and its response time and the time to request and receive the meter result.

There is a case for building it and gradually reduce the time allowed for each part of the measurement until you get inconsistent results.
 

Picbuster

Joined Dec 2, 2013
998
Step one: define the time to measure one line. Handle as being already connected.
Assume Mt (total measure time)
You use a Rs232 connection to start the sequence (mpu is doing the job) or are using this line to control mux?
in either case define the time needed to select St( select time) next port.
Same thing but now reading Rt.
Your cycle = Mt+St+Rt+To (To turn around time needed to switch from transmit to receive and back)
Calculation is impossible without variables as mentioned above.

Picbuster
 

MisterBill2

Joined Jan 23, 2018
6,018
OK, so the question is about settling time of a meter circuit measuring resistance. But if you are performing automated testing then the whole thing gets much more complex. Not only must the meter measure the resistance but some part of the system must receive that reading and compare it with the accept/reject limits for that multiplexer position, and then generate a signal that some other portion of the system must respond to. So there are a number of different time intervals involved.
Without being at all nasty or sarcastic I am asking for quite a few more details, starting with the range of resistance values involved and the type of multiplexer being considered or used already. Then there is also a question as to what is the meter actually doing? An explanation of the process will allow the smart people in this forum to provide some good advice, and hopefully quiet some of the noisy ones a bit.
 
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