I've had a good read of the openenergy site and am still slightly confused in relation to the various different modules which are available.
I'm trying to determine the most cost effective way of using multiple temperature sensors and was initially looking at 2-3 of the "emonTH 433MHz - Temperature & Humidity Node" (http://shop.openenergymonitor.com/emonth-433mhz-temperature-humidity-node/) devices. (I will want to connect multiple DS18B20 sensors to each).
Then I spotted this link (http://openenergymonitor.org/emon/emontx/tempnode) which I assume is relating to the V2 PCB (http://shop.openenergymonitor.com/emontx-v2-pcb/). What I'm not sure about is this just a kit version of the above module or is it different (i.e. different PCB and/or functionality).
Then I've also seen the "emonTx Arduino Shield SMT" (http://shop.openenergymonitor.com/emontx-arduino-shield-smt/) too...
Is the a simple comparison between these options.
Should any of these options be considered obsolete in any way.
Thanks in advance.
Re: Confusion over the different hardware modules
Fundamentally, all the options you mention use the same hardware - an Atmel ATMega 328P and the software they use is fundamentally the same too, a OneWire interface and temperature library.
The first point to know is, there is no limit to the number of sensors - in theory. In practice, the cabling scheme you adopt and the cable lengths will impose a limit, and the standard sketches also have set maxima - though these can be changed.
The EmonTH is designed for battery operation but it can be powered from a 5 V USB supply.
emonTx V2 is obsolete - only the PCB is available now, you'll have to source the rest of the components from the usual places, unfortunately. The emonTx is principally a voltage and current measuring module, so much of the PCB will be unpopulated. You can think of the emonTH as a stripped down emonTx without the electrical measuring side. It needs a 5 V USB supply.
The emonTx Shield is a shield for the Arduino Uno, so it provides the connection interface and the radio module for the processor in the Arduino to control. This too has voltage and current inputs that will be redundant. It needs a 5 V USB supply.
What you haven't mentioned is how you are going to handle the data and where - that could have a bearing on what's best for your application.
There's an article in Resources|Building Blocks about the DS18B20, and papers linked from that, that are worth reading.
Re: Confusion over the different hardware modules
What you haven't mentioned is how you are going to handle the data and where - that could have a bearing on what's best for your application.
If you are planning to use a Pi to collate or forward your data, you could connect the 1-Wire temp sensors direct to that if you have no other sensors.
emonTx V2 is obsolete - only the PCB is available now
This WAS the case I know, but I noticed sometime ago the kits have reappeared, only the rfm is not included. However, in this instance if only being used for 1-Wire then the bare boards with just the necessary components maybe a better option
Paul