Logging data from Milone eTape

Hi Eric – I’ve purchased and looked at using the eTape.

I was just wondering what made you think they are “calibrated” – that is the “0.0” markings relates to a defined voltage.  Usually this is shown for a calibrated sensor.  Similarly for a Full Scale relates to a known Voltage.?

looking at the graphs,  they describe “0-5VDC Linear Resistance to Voltage Module PN-05V00199 REV 2” but no graphs of 0.0 to V

https://img1.wsimg.com/blobby/go/ab87a52f-5721-46e1-a348-7722f5ddcf97/downloads/0-5%20VDC%20Module.pdf?ver=1737319366040

Be interested if you find that they have it calibrated .

Good to hear. and definitely very interested in use with a flume.  What range of water depth measurement are you looking for and depth accuracy of measurement.

Typically, because  ADCs are not good around 0.0V and rail – the Sensor range from 0.0 to full range, the Voltage range is from 10%Rail to 90%Rail (eg 0.3V to 3.0V for 3.3VDC rail) and typically wants to be ratiometric. That is the ADC voltage VREF is the same as that used by the sensor.  The other way of adjusting that is that the measuring device has a greater range than the actual range of measurement. That is 0.0  is less than the flume entrance.

Resistance  varies with temperature (as everything in the universe varies with temperature)- so they haven’t listed what the temperature dependency is.   It might not be much in the water, and may need a reasonable shield for that out the water.

How are you looking to power it, Are you looking to report it wirelessly?   Standard ModularSensors is best effort in both cases.

Hi Eric. this is a voltage sensor, so it fits a pretty basic type of sensor, measure the voltage and then translate it to depth.

For a sensor, layers of calibration give value. Calibration of the sensor to defined units (V to mm), and calibration of the water height to the measured height in the flume.

The accuracy sounds pretty reasonable, for a visual check can probably can only get to +/ 1mm visually under ideal circumstance.  There are some good ideas of attaching the sensor into the water https://www.envirodiy.org/knowledge-base/ Sect 7.3.4 – however each time is going to require mapping to a physical measurement tape line. So how to secuse the milone tape in a a protective pipe and also relate to its calibration. Might be an idea to have a see through protective plastic pipe, to map milone tape measurements to external physical reading

For the milone tape output, the auxiliary ADC. ADS1115 gives the most accuracy with an input over 0 to 3.3V. You need to decide if running it at switched 3.3V or boosted 5.0V.   I would think 3.3V

I did see this discussion, that is using a 0-10V , but would need to scale it to 0-3.3V

https://docs.google.com/presentation/d/1LqyQEa3EJx3xvbQfo6V8wqlVyj3OxlF3AZsk2E7ZLn0/edit#slide=id.g149c4d18368_0_1

https://envirodiy.github.io/ModularSensors/group__sensor__ads1x15.html

I should point out that main ModularSensors is a “scientific software” package – best effort architecture. Nobody is sharing metrics as to how well it works, which is usual practice for engineering types. Engineering is about high reliability, software and hardware.  There are some good software examples, but no standard software reference builds. If there is good wireless cell signal,  then readings on the server (assuming MonitorMyWatershed ) gives a good visual that the site is operational If the wireless or server becomes unavailable, readings are dropped – however its accessible on the loggers uSd card.  If the available power in the battery gets low and not managed the processor starts resetting and needs a site visit and new battery. So I recommend one of your sensor be the battery and also the  SampleNumber – a linear number increments each sample and reset to 0 when the processor boots. https://envirodiy.github.io/ModularSensors/group__sensor__processor.html

I’ve done my own fork of ModularSensors to make it as reliable as a “Walking Boot Net”, that is walking up to the logger and copying the uSD to get ALL the time series readings. Features here  https://github.com/neilh10/ModularSensors/wiki/1a-Feature-notes

Description of my systems that have been operating in the field for some years https://www.envirodiy.org/n-ca-mayflys-through-the-winter-storms/ 

I did do a crude Electrical Conductivity sensor – measuring the waters EC through a simple sensor, and no wireless – I don’t think this is going to be that helpful but this is where it is – https://github.com/neilh10/ModularSensors/tree/release1/examples/tu_ec01

Goodluck