neilh

For a fully built commercial offering this has just been announced. Select only the 4-20mA Input Adapter
https://www.onsetcomp.com/products/data-loggers/rx2100

So to restart the thread – it can be done with RS485 wing board to generate a switched excitation voltage (from the LiIon). The voltage probably needs to be 14V+ so could be U3V50F24 to generate 24V.
To measure the 4-20mA accurately use Adafruit INA219 with a 10ohm resistor.
https://www.adafruit.com/product/904
The Mayfly has the INA219 drivers,…[Read more]

Hello Mark – oops I’m thinking in another dual world – my brain fart.
The sensor is 4-20mA (i’m using that type of sensor in non-mayfly Onset U30 loggers and trying to move to Mayfly/RS485).
The 4-20mA with excitation 12-36V is much simpler, but it is not supported directly by Mayfly.
The excitation voltage can be done with the switched…[Read more]

It sounds like the RS485 Wing Shield would work for you, probably standard voltage option but you should check it works. It does require assembly and soldering.
I was wondering if you have the sensor manual including data protocol and what RS485 registers,

Hi Mark
Thanks for sharing – just wondering what your power supply source is. Are you solar powered, running of the LiIon battery or another source.
Technically the spec says “Power Supply:12~36VDC” – that is nominally 24V, but actually a range. That would fit with the…[Read more]

Cal – Some thoughts, if you are using the Mayfly’s battery measurement its not actually measuring the LiIon battery voltage. How are you connecting the solar cell and what rating is it?
If the battery is charging, its taking current and the voltage indication is close to that of the battery – depending on how much solar there is. For the voltage…[Read more]

Unfortunately I am seeing some issues with the LiIon battery measurement. I think the issue is that the battery measurement uses a 10M/2.7M resistor with a high impedance Analog input, and if its in an RF noisy location (roving cell phones) it can detect some of that energy. Wires can behave in two ways – on the one hand they conduct current,…[Read more]

Hello Jesse, great you joined.
Can you need to provide a bit more information.
It is **normal** ~ though perhaps undesirable and non-intuitive ~ for a depth measuring instrument to show a slightly negative depth when outof water. Depending on the type of physical sensor they don’t know 0.0 – they have to be calibrated for it, and even that,…[Read more]

Wow. Thankyou Stroud Water team for detailed how-tos. Fantastic stream side setup for Mayfly, as well as good reference material for how to do water quality collection.
One comment, is that we’ve seen sensor cables being gnawed. So we’ve tended to put the cables communicating to the sensors in a flexible PVC sheath. In the West we also get…[Read more]

that sounds pretty fantastic. Of course doesn’t indicate long term reliability and the issues are mechanically how to connect the water pressure with the mineral oil. I’d be interested in how you are thinking about doing it in a steam with the logger connection is say 20′ above the point of measurement. But its giving me someother ideas. I’m…[Read more]

BME280 – I don’t know. Its a materials/chemistry issue – how does mineral oil react with the materials in the sensor. Probably easy to test – but how to do longer term reliability testing.
Years ago, a Motorola/Freescale product “Pressure sensor” engineer suggested I use a high molecular silica gel for interfacing to its air sensor diaphgram.…[Read more]

Hi John – feel free to email me direct on neilh at biomonitors.com as I get it quicker.
comments: generally pressure sensors are pretty easy to understand and calibrate for a water column – but the devils in the detail. What range (eg 0-10′) and accuracy do you want.
1) for the BME280 it hasn’t got an easy mechanical port to isolate the pressure…[Read more]