Multiple Optical Utility Meter LED Pulse Sensor connection to EmonPi

Peter_Randall · 2024-01-03T15:29:16.146Z

I have two sub-meters in a property which I need to monitor, matching the actual meter reading. In theory this should be possible using the Optical Utility Meter LED Pulse Sensor. These are supplied with a RJ45 plug. However the EmonPi has only one RJ45 connection which would normally be used for the internet connection.
Which of these would provide the best solution and will it work?
RJ45 to USB adaptor(s),
Use a network switch,
Use an emonPi / emonTx RJ45 to Terminal Block Breakout for DS18B20 board plus a USB adaptor,
or is there a better way?

How is each pulse sensor seperately recognised?

Thanks in anticipation of any help.

Robert.Wall · 2024-01-03T21:57:06.160Z

Peter_Randall:

However the EmonPi has only one RJ45 connection

I think you are confusing the RJ45 CONNECTOR with an Ethernet connection. The emonPi does in fact have two RJ45 sockets, one is Ethernet (labelled as such) and the other is simply an 8-pole connector which is used for the pulse and temperature inputs. This one is clearly labelled "RJ45 I/O - DS18B20 - IRQ/PWM.

Peter_Randall:

How is each pulse sensor seperately recognised?

The answer is, using your suggestion, they would not be. The emonPi has only one pulse input while it also has the radio module. It can never have three. You cannot do it the way you suggest. The best suggestion I have is to use a separate Raspberry Pi and connect the optical pulse sensors directly to the GPIO inputs.

This is for 2 sensors and a Raspberry Pi - but I don’t know a good reason why you could not extend it to three:
Directly connecting to Optical Pulse Counter with RPi? - #2 by pb66
or there’s this with a Raspberry PiZeroW:
Pulse sensor RPI directly - #3 by borpin

There are 3 connections to the optical sensor. 2 & 5 are +5V & GND respectively, 6 is the output. It is not in fact a pulse, in that there is no control of the shape of the output using (say) a Schmitt trigger.

You’ll need @pb66 's Python script etc (possibly modified - I’ve not looked at it) to do the pulse counting as he describes.

Peter_Randall · 2024-01-04T10:41:17.595Z

It will be more effective but much more expensive to use SDM120 modbus meters and USB to RS485 adaptors. Multiple units can be connected as documented in the heat pump monitoring documentation.
Just a shame that an easy to implement and cost effective solution is unavailable.

Robert.Wall · 2024-01-04T12:33:38.050Z

I didn’t think you were interested in heat pumps, and I offered the best suggestion that’s been documented on the forum - which you’d clearly not found. If you don’t want to adopt it, fair enough.

Peter_Randall · 2024-01-04T17:40:00.304Z

Sorry if my reply sounded churlish. I always look for simple solutions. It has to be remembered that many users do not have an indepth knowledge of Python and are reduced to copy and pasting, which most times work. When it doesn’t or instruction is unclear where to insert a script, life becomes challenging to say the least.

The meters can be used without a heat pump. In this instance they willl be used alongside one. Connecting the heat meter is a whole different kind of fun. The scripts for the modbus meters and adaptors look straight forward. The 100A SDM230 modbus meters are currently available at a good price (35% less than SDM120) and far less fiddly to install. They are also listed on the Emonhub Interfacer page and the script ReadME.

Wish me luck!

TrystanLea · 2024-01-04T22:43:18.503Z

Hello @Peter_Randall are you talking about an emonPi v1 or the newer emonPi v2? With the emonPi v2 it is possible to arrange up to 3 pulse inputs (2 easily as they are linked directly to the RaspberryPi, a 3rd can be configured in place of the analog input on the micro.

The RJ45 socket on the emonPi v2 is for the AC voltage sensor only. It does not support the Optical pulse sensor RJ45 plug. See: Other sensors — OpenEnergyMonitor 0.0.1 documentation

Peter_Randall · 2024-01-05T15:52:28.502Z

Hi Trystan. Thanks for your reply. This is my third OEM install, this time in a self catering property we own. It is part of a major project installing a new wet heating system with an ASHP. The monitoring is important but secondry to everything else involved. Also need to upgrade metering as mentioned at the start of the thread. Currently have two smart meters, one PV generation and the other an EV charger to charge money to guests using it. The Logging service provider has lost interest in providing a good service, no longer providing real time data. Due to previous reply, currently don’t have time to mess around and have ordered three SDM230 modbus meters and USB adaptors. I need a reliable real time solution and am hopeful this will provide it.

Due to issues trying to get a Sontex 531 communicating via a Packom hat (second project and still not resolved) have ordered a mbus to usb adaptor from China, same as one currently unavailable in the OEMshop. Am hopeful the Sontex Supercal 5 ordered will work without too much grief. Only question now is an Emonpi V2 really needed or can an Emon Base make do?

There is a whole thread on my efforts to get the Packom hat working which you kindly contributed to (Packom Pi HAT for Mbus & heat sensors - #10 by glyn.hudson). I ran out of time as being out of the country for 3 months from not long after the last post in the thread. On return, between other priorities and the limitations of my knowledge of Python, I haven’t been able to motivate myself sufficiently to get it working. I may need to find a tame Python expert to put me right.

The OEM platform is really good, but can be unforgiving of those without quite a bit of in-depth programming knowledge.

TrystanLea · 2024-01-06T14:55:00.645Z

Peter_Randall:

have ordered three SDM230 modbus meters and USB adaptors

Good call. The data output from Modbus SDM meters is much better than pulse counting.

Peter_Randall:

Only question now is an Emonpi V2 really needed or can an Emon Base make do?

Sounds like the emonBase is perfectly suitable for what you are doing there if it’s just the MBUS and MODBUS inputs via USB.