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Elster v200 water meter pulse count

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I’m attempting to monitor water consumption with my emonpi. My meter is an Elster v200 and I bought an Elster PR6 pulse counter

I know others started working on similar setups but I didn’t see any reports of success. E.g.

Relevant facts about the Elster PR6:
– the red CH2P wire is the secondary pulse output (compensated for backwards flow)
– the black GND wire is common/0v
– the PR6 expresses K-factor as x:y where y is the factor of the CH2P wire. In my case y=1 so 1 pulse will be 1L
– outputs are all “open drain”
– PR6 data sheet illustrates an output pulse as being a short ‘0’, with a ‘1’ when not pulsing (as a complete newbie this was a surprise to me, I expected a pulse to be a logic ‘1’)
– pulse width is 80ms

Pull-up resistor or not?
– the PR6 data sheet says the outputs may be connected via pull-up resistor to up to 30v. It makes sense intuitively to me to connect a pull-up resistor between Pulse and Power so that when not pulsing, the output is held high. There is a picture in an Elster guide showing a 2.2kohm resistor used for this purpose
– HOWEVER, there is a comment on the ever-helpful Wiki on the RJ45 connector (https://wiki.openenergymonitor.org/index.php/EmonPi#RJ45_Socket), that there is an input pull-up already inside the IRQ input

So I decided against a second pull-up resistor, and connected the red PR6 wire (CH2P) to Pin 6 of the emonpi’s RJ45 connector; and the black PR6 wire (common) to Pin 5 of the emonpi’s RJ45.

So far pulse count appears to be well in line with the metered usage, so I am optimistic, but am woefully underqualified so hope that an expert can correct any major bloopers and perhaps this will help anyone with the same setup

Thanks
Chris

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Nice to see you have found a solution.

Both of those are correct. However, there’s been a post very recently that I responded to where the user had initially connected a pulse output the other way round and fitted a pull-down resistor, which was competing - and they experienced noise in the c.t’s current reading. They changed it round, but had a quite long cable and adding a second pull-up in parallel with the internal, quite weak one, all the noise problems seem to have gone away. (Water meter pulse input causes CT noise on emonPi)

So if you have a short cable run, what you have done should be fine. But if you get spurious pulses, then consider adding an external pull-up.

Thank you Robert, good to know! (My cable run is short so hopefully no issue)

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Hi Robert, you were right, I was seeing some spurious pulses and so am experimenting with different additional external pull-up resistors, which definitely help. The spurious pulses which are hard to eliminate occur when a 3kw immersion heater (connected to the same emonPi as the RJ45 pulse counter) switches on or off.
Thanks again
Chris

If possible, route your cable away from the cables carrying the immersion heater load and away from the meter tails. If you have to cross either, do so at right angles.

Hurray! That worked! I’m chuffed, thanks for the hint. Time for some TV and alcohol now, my IQ needs lowering after spending the last few days on these forums…

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