[Shannon Hicks]

The polarity of your battery pack is backwards, which is why your board was damaged.  We mention the caution about battery polarity in multiple places on this website, and also in the EnviroDIY Monitoring Station Manual, and specifically in Section 6.1 (https://www.envirodiy.org/knowledge-base/building-an-envirodiy-monitoring-station/).  I’m attaching a photo of that part of the manual, showing the caution note and a photo showing the correct polarity.  About half of all JST 2.0 battery connectors are backwards, there’s no industry standard that states which pin is positive and negative, so it’s up to the user to confirm the proper polarity before connecting anything.  It also appears that the JST connector you have connected to the external power input is also backwards from what we always use with our loggers and accessories.

 

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   manual_capture_6.1.png
   

[Shannon Hicks]

We’ve installed several stations in tidal areas by attaching the sensor to a custom apparatus mounted to docks or piers.  What kind of sensors are you planning to install?

[Shannon Hicks]

Yes, the update made to the ModularSensors code in in order to fix Hydros 21 is backwards compatible.  I mentioned it last week in this post: https://www.envirodiy.org/topic/hydros-21-decagon-ctd-reading-error/#post-17066

It seems that in the past year Meter Group made some changes to the amount of time the CTD sensors need to take a measurement, so we increased the wait time from 500 milliseconds to 1000 milliseconds.  If you use the new code to talk to an older sensor, all you’re doing is waiting an extra half second, so there’s no reason to keep the old code.

[Shannon Hicks]

When you’re connected to the Mayfly with your computer, open the Arduino IDE’s Serial Monitor and check the settings of the dropdown box in the lower right hand part of the windows next to the baud rate.  It should be set to “No line ending”.  If you have it set to anything else, you’ll usually get an error when setting the address using that sketch because you’re sending it the address character AND a line ending or carriage return.  Saying “No line ending” should fix it.

[Shannon Hicks]

Yes, it’s just one line (currently line 107) of the MeterHydros21.h file that contains the most important change, which is this line:  define HYDROS21_MEASUREMENT_TIME_MS 1000

The previous setting was 500 milliseconds but it turns out the new Gen 2 CTD sensors need a full second for measurement time, so changing that line will allow you to use the Gen 2 Hydros21 sensors.

[Shannon Hicks]

We’ve seen this behavior with some of the new CTD sensors as well.  It seems that when you give it a new address using the b_address_change sketch, the sensor needs to be told the new address more than once in order for it to actually make the change.  Meaning, run the sketch and observe the text on the Serial Monitor.  For a new sensor it will say sensor found at address “0”.  Type “1” into the text box and press Send.   It’ll then say the sensor is now found at address “1”.   However, you should do it at least a few more times.  Enter “1” into the text box again and press Send.  It should say sensor found at address “1” again.  Try it at least 3 or 4 times, and then you should be able to unplug the sensor, upload your logging sketch, and the sensor will be found at address 1.

You should also make sure you’ve updated you libraries files recently.  The new version of the CTD sensors required a slight change in the SDI-12 protocol instruction timing, and those changes are incorporated in the latest version of the EnviroDIY SDI-12 library.  You can either update just that one folder, or all of them using the EnviroDIY Libraries zip file found at https://github.com/EnviroDIY/Libraries

If you’re still using an SDI-12 library version from prior to April of this year, it won’t work with the new CTD sensors and you’ll get -9999 for all parameters even if you’ve got the correct address programmed to the sensor.

[Shannon Hicks]

Thanks for the followup.  Plugging an EnviroDIY sim7080 LTE bee board into one of the old Digi bee adapter boards will definitely cause problems, since there are different pinouts for the 2 cell modules, as well as different supply voltages provided to the pins, which could damage the sim7080 bee.  Also note that upgrading a Mayfly board from a Digi cell board to an EnviroDIY sim7080 bee board also requires a different logger sketch to be uploaded to the Mayfly board, since the commands for cell module libraries are different.  Examples of sketches for both the Digi boards and the EnviroDIY sim7080 LTE boards are available in our ModularSensors github repo.

[Shannon Hicks]

For anyone reading this in 2022, the posts above in this thread are from 2016 to 2019, and the operating voltage and other electrical specification have changed with the Mayfly boards released in the past year.  The older Mayfly v0.5 boards had completely different input voltage limits compared to the new Mayfly v1.0 and v1.1 boards.  So the advice above about connecting 12v batteries directly to the Mayfly is not applicable to the new boards.

For v0.5b, LED3 should only be on if the mosfet transistor on the Mayfly is turned on, which should only happen if you set pin D22 to high in order to turn on the switched sensor output power circuit.  If yours is on all the time, or partway, then either that mosfet is electrically damaged, or there’s something wrong with another part of the board.  Since you’re saying the onboard ADC is not always right, then my guess is that you’ve got a tiny bit of corrosion somewhere on the board (probably around the main processor chip in the center) that’s causing noisy input to the analog ADC input pin, and also causing D22 to appear high, triggering the mosfet.  Has your board been subjected to high humidity and/or condensation?  Or ants?  We had a station start malfunctioning after a few tiny ants made their home in the logger box and laid some eggs on the circuit board, resulting in corrosion and failure of the Mayfly after just a few days.

And if you’re still using a Digi LTE module with EnviroDIY LTEBee adapter, that could be contributing to the odd behavior as we saw lots of random failures of those due to a still-unresolved issue with the Digi boards, which is why we stopped using those cell modules and designed our own.  Have you tried removing all sensors, the solar panel, any external power sources, and the cell board and just operate the station with nothing attached but a lipo battery and/or a USB cable to see if it operates normally and records data to a card?

[Shannon Hicks]

That station appears to be running the older configuration of Mayfly v0.5b and Digi LTE board (with an EnviroDIY LTEBee adapter in between the Digi board and the Mayfly), correct?  There could be several reasons why it’s behaving like that, and it’s difficult to tell unless you start swapping parts or disconnecting things one at a time to see which thing is causing the issue.  The first thing to check would be the datacard file on the logger to see if the logger is still operating and recording data to the card even though it’s offline.  Once you know that, it’ll help us narrow down the problem.  The other quick thing to do would be to put a different lipo battery pack on the board and let that run for a few days.  We’ve seen failing battery packs cause all sorts of strange issues that were resolved by simply replacing the pack.

[Shannon Hicks]

No estimate yet, I’m still working on the redesign and will then have to get them manufactured once we’ve fully tested them.

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