Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, an initiative of Stroud Water Research Center designed to help people advance knowledge and stewardship of fresh water.
New to EnviroDIY? Start here

Reply To: GPRSBee

Home Forums Mayfly Data Logger GPRSBee Reply To: GPRSBee

Adam Gold

    I’m having a similar problem with the LTE-M Xbee3 that folks in this forum have already described, but slightly different. I have the same hardware as Cal and Brian, but I have a Taoglas LTE-M/NB-IoT antenna. Using the menu_a_la_carte.ino from Modular Sensors, the modem will throw a lot of “NO RESPONSE” messages while trying to synchronize with NIST, and the cell signal strength and % will be displayed as -105 and 12 when written to the SD card. It is getting a good amount of signal when I connect the modem to XCTU with an XBEE explorer-type board, but it takes a few minutes to connect. I tried using some simple code with AT commands that was posted in the “Trouble Initializing XBEE LTE-M” forum to wake it up and reset defaults, but it only responds about half of the time to the “+++” commands and never responds to AT commands with StreamDebugger.

    I switched from using the main branch of Modular Sensors to the develop branch, but I got the same kind of response. I then changed up some of the “timeout” values in “TinyGSMXbee.h” and got this response:

    Sending data to data.envirodiy.org
    08:54:25.650 -> POST /api/data-stream/ HTTP/1.1
    08:54:25.650 -> Host: data.envirodiy.org
    08:54:25.650 -> TOKEN: [my token]
    08:54:25.650 -> Content-Length: 402
    08:54:25.650 -> Content-Type: application/json
    08:54:25.650 ->
    08:54:25.650 -> {“sampling_feature”: [my sampling feature]}
    08:54:25.650 ->
    08:55:17.649 -> — Response Code —
    08:55:17.649 -> 504

    I could see that the modem was trying because the Hologram Dashboard showed activity, but my values for cell strength were all zero. I modified some code in EnviroDIYPublisher::sendData to try and increase the waiting time for a response from the data portal:

    After this change, I got a similar response, but there are no “NO RESPONSE” codes, a “Bad timestamp, not setting clock.” message, and my data were sent to the portal once. Every time after that initial upload to the data portal, I will get a 504 response code. The cell strength and % were still reported as zero even when it uploaded to the data portal. Output showing initial successful upload:

    Setting up sleep mode on the XBee.
    08:46:28.963 -> [2797] ### Modem: Digi XBee3™ Cellular LTE-M
    08:46:29.308 -> Attempting to synchronize RTC with NIST
    08:46:29.308 -> This may take up to two minutes!
    08:47:06.473 -> Bad timestamp, not setting clock.
    08:48:01.713 -> ——————————————
    08:48:18.506 -> Successfully connected to SD Card with card/slave select on pin 12
    08:48:18.540 ->
    08:48:18.540 -> \/—- Line Saved to SD Card —-\/
    08:48:18.540 -> 2019-02-01 08:48:00,2,-9999,11025,4.761,30.25,0,0
    08:48:18.574 ->
    08:48:18.574 ->
    08:48:26.027 ->
    08:48:26.027 -> Sending data to data.envirodiy.org
    08:48:42.099 -> POST /api/data-stream/ HTTP/1.1
    08:48:42.099 -> Host: data.envirodiy.org
    08:48:42.099 -> TOKEN: [My Token]
    08:48:42.099 -> Content-Length: 402
    08:48:42.099 -> Content-Type: application/json
    08:48:42.099 ->
    08:48:42.099 -> {“sampling_feature”:[My sampling features]}
    08:48:42.099 ->
    08:48:45.941 -> — Response Code —
    08:48:45.941 -> 201

    Does anyone have code that consistently works with the LTE-M Xbee3 or suggestions on how to proceed? I am hoping to have a total of 10 stations that each have an LTE cell modem so they will work for a long time, and I don’t want to invest in the LTE-M Xbee3s if they’re not dependable. Are there other LTE cell modems that are known to work easily with a Mayfly like the Digi 4G LTE Xbee or the Digi 4G LTE-Cat1 Xbee3?