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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?