RAK 7205 - Stops reporting / reports inconsistently

Hi,

I have a RAK 7205 mounted on a vehicle in a farm lorawan setup. It was reporting intermittently for about a week then stopped reporting altogether. I’ve since connected to it via usb and it has now jumped back to life, however even when left in the same spot in direct sunlight in the backyard it continues to miss sending observations. Currently i have it configured to send every 10 mins. Please see the attached graph that shows how often it managed to report over a 3 hour period.

Q. If the device wakes up and fails to get a GPS satellite fix should it still send a lorawan packet? i.e my expectation would be to see a packet every 10mins or so with some being error readings if the device failed to find a satellite.

Q. Any tips for how to debug what is happening here? When it is indoors and connected to my pc i can’t seen any obvious error conditions. I would like to be able to check if it is successfully waking up every 10 mins, if so is it failing to get a satellite fix etc.

Q. Assuming sunny conditions and the solar panel is operating at max capacity what would you expect to be the max frequency you could send observations without running the battery flat? i.e is every 10mins to often?

Q. Basically i was hoping to recreate a ‘strava (iphone app)’ like experience where i would have enough data to map where a vehicle had been and how fast it was going at different points during the trip. My ideal scenario would be reporting sensor observations as often as every 5 seconds while the vehicle is in motion. Is this type of usecase supportable with the RAK7205?

Thanks,
James.

Welcome to RAK forum @jousby :slight_smile:

To answer your questions:

  1. The device will still send LoRa packets even without GPS signal. But of course no GPS data.
  2. The debugging depends on what you are trying to figure out. I am not sure where you get the graph. But probably add another extra device (if you have) that can send every 2 minutes to see if the gateway side and network server is working ok. If your 2nd device continuously transmit and the RAK7205 do not, then it is the device issue and not a GW or LNS related. How far are you from the gateway btw and what LNS (LoRaWAN network server) do you use? Do you own the gateway and have access to it?
  3. This is something need to be tested on the field. We need to get the charging current of the solar panel (probably average for the whole day) then match it to the discharge current of RAK7205 (which will depend on the frequency of sending uplinks).
  4. Every 5 seconds transmission will not work on ANY LoRaWAN devices because of the duty cycle and dwell time restrictions depending on where you are.

Btw, I suggest you update the FW of your RAK7205 in case it is not yet updated - Quick Start Guide | RAKwireless Documentation Center

Hi,

Thanks for the quick reply.

I’ve now done a firmware update but the behaviour remains the same. As in the device seems to wake up at random times not at the fixed sending interval. It does this during the night as well so seems to be unrelated to how much charge is in the battery and how much is being recharged by the solar panel.

I’m using the AWS IOT Core for Lorawan as my LNS with a Laird Sentrius Gateway. The graph above is generated from AWS Cloudwatch logs where I’m recording all the inbound messages. I have several other sensors running on the same setup without problem. I’m fairly confident its not the gateway / LNS setup.

The sensor is setup (at the moment) about 5m from gateway.

I’ll keep trying a few things on my side but if you haven’t seen this before in a RAK7205 perhaps my device has a hardware fault?

What frequency band do you operate? Does it occur only if purely battery powered? Or even when connected via USB (power or data)?

We have issue on RAK7205/RAK5205 that halt transmitting after long time of continuous operation. That is solved already by the latest FW. But in your case, it suddenly occur (the erratic behavior of not transmission).

Hi James,

I have exactly the same problem. I tried a 7205 on my tractor and a RAK7258 gateway.

I’m new to IoT and thought it would be interesting to try something similar on our small vineyard. As a strava user I was also keen to visualise tractor movements e.g. where I mow most and perhaps build up a heat map type visualisation, but I realised that the 7205 can only send location updates every 10mins which is no use for a fast moving object (I might try putting it on one of my sheep to view grazing habits!).

But timing aside I have found the battery and lorawan range seem to be very intermittent. Basically the 7205 only works if I bring it inside and sit it next to my gateway, and then it has to be by a window to get solar power and GPS.

I guess the the 7205 is as it says - very much a learning device.

If you are interested I’d be keen to hear more about your projects and exchanging ideas.

Cheers, Simon

Hello @sossie07 , welcome to the RAK forum.

The RAK7205 has an AT command to change the send interval:

at+set_config=lora:send_interval:X:Y

Parameter Description
status Enable/disable the mechanism for sending data in intervals.
0: the device will not send data automatically.
1: the device will send data every ‘interval’ seconds.
interval Time in seconds. This parameter is only valid if ‘status’ is set to 1.

For the range, if your gateway is inside the house, your range will be limited.To achieve the best range, your gateway antenna should be installed as high as possible and outside of the house.
Also keep in mind that LoRa works best with an un-obstructed view between the gateway and the RAK7205.

Here is an example:


Vineyard 1 should be no problem for the RAK7205, Vineyard 2 is shadowed and you will mostlikely get no packets to the gateway.

Thanks for the response Bernd. I didn’t realise I had to use the X:Y, I was just using Y

If I try to set the send_interval to something other than 600, it seems to be pretty random as to what actual interval it will actually send. I would like to get it to send at least every 60 seconds (20-30 seconds would be ideal), but if I set it to 30seconds, it only sends every minute or so. I turned the gps search interval down to 20 seconds in case that was delaying it.

I think the problem with mine is that the battery does not charge well, so either the solar or the battery has a fault and I can only use it for any length of time plugged into the usb. I believe I need jumper J11 removed for battery power and this is the case. Its a brand new device.

Thanks for the advice.

I have to ask our engineers, but my guess is:

Wait for send_interval time finished
Try to get GPS location fix, 10 to 90 seconds (or the limit you set)
Wait for send_interval time finished

Which will lead to a different send interval, depending who long it takes to get a GPS location fix.

Like

If I were designing for this use case I’d try to run a scheme where the node could get power from a vehicle electrical system while in motion, and only rely on solar/battery when off. That could also correlate with more frequent transmission whenthe engine is on, and less frequent otherwise

Debugging wise it would be great if there were a way to get direct debug output via a UART rather than USB that’s coupled to power, so that a logger could be temporarily placed next to it to record and timestamp debug messages during a period of field usage with the actual field power situation.

Recording data on board for later physical transfer can have use, too.

One thing it should be possible to do even with the current setup is see if the LoRaWAN uplink frame count is smoothly advancing or jumping, which would hint at how often there are missed transmissions between the received ones, vs the node for whatever reason not even transmitting at all.