xdot skipping one frame in class C

[alejandro ballesta]

Hi all,
we are using the xdot-eu in class C. Also node is setup as class C in the conduit gateway.
AT+DLC is checked every 30s to see if something new has arrived, if the counter has increased we get the data using AT+RECV.
So far so good.
The problem we are facing is that we send frames to the node but the DLC is increasing in steps of 2. It’s like the node is skipping one frame.
Checking the /var/log/ we see the gateway is indeed sending the packet.
Also checked the modem is serial mode and the same happens.

Any idea?
Thanks

[Jason Reiss]

What versions are you running for xdot and lora-network-server?

Do you see the missing frame counter being sent in Conduit logs?

The counter will be sent from the network server, the dot will just display what was received.

[Jason Reiss]

The latest version seems to be OK, no missed frames.

admin@mtcdt:/var/log# /opt/lora/lora-network-server –version
MTS Network Server – Version 1.0.37

Have a look at the DOT logs too it will show all received frame counters.
[INFO] Packet Received : Port: 1 FCnt: 00000002 Size: 1 ACK: 0 DUP: 0

[alejandro ballesta]

Hi Jason,

thanks for your reply

/opt/lora/lora-network-server –version
MTS Network Server – Version 1.0.18

MultiTech xDot
Firmware: 2.0.14-(detached from 3699e9b)
Library : 2.0.14-(detached from 7f6b74e)

Here is an example of two consecutive messages sent

/var/log/`
8:50:27:64|INFO| Queue app data 2 bytes
8:50:27:65|INFO| Scheduled 5 bytes payload
8:50:27:325|INFO| Frame transmitted to 00:00:00:06 via GW (00:80:00:00:a0:00:0d:b5 Chan FC1 127.0.0.1:56959) Seq# 6
8:50:27:329|INFO| Check response size: 00000006 sf: 7 bw: 0 dur: 10 < tm: 51 wnd: 2
8:50:27:330|INFO| TransmitQueue canIncreaseDuration tmst: 412279129 us dur: 51 ms 0
8:50:27:336|INFO| Update DC Band: 2 Duration: 0 time-on-air available: 360000 ms
8:50:27:336|INFO| Transmit UDP message to Gateway 242 bytes

8:51:14:231|INFO| Queue app data 2 bytes
8:51:14:231|INFO| Scheduled 5 bytes payload
8:51:14:492|INFO| Frame transmitted to 00:00:00:06 via GW (00:80:00:00:a0:00:0d:b5 Chan FC1 127.0.0.1:56959) Seq# 7
8:51:14:495|INFO| Check response size: 00000006 sf: 7 bw: 0 dur: 10 < tm: 51 wnd: 2
8:51:14:496|INFO| TransmitQueue canIncreaseDuration tmst: 412326297 us dur: 51 ms 0
8:51:14:498|INFO| Update DC Band: 2 Duration: 0 time-on-air available: 360000 ms
8:51:14:498|INFO| Transmit UDP message to Gateway 242 bytes`

I believe the data is really being sent. Here you can find the output of the mqtt subscriptions

lora/00-80-00-00-04-00-1e-e7/down { “data”:”CgE=
“}
lora/00-80-00-00-04-00-1e-e7/packet_sent {“appeui”:”2b-7e-15-16-28-ae-d2-a5″,”data”:”YAYAAAAABQABxux+goOk”,”datr”:50000,”deveui”:”00-80-00-00-04-00-1e-e7″,”fdev”:25000,”freq”:869.52499999999998,”imme”:true,”ipol”:true,”modu”:”FSK”,”ncrc”:false,”powe”:14,”rfch”:0,”size”:15}

lora/00-80-00-00-04-00-1e-e7/down { “data”:”CgE=
“}
lora/00-80-00-00-04-00-1e-e7/packet_sent {“appeui”:”2b-7e-15-16-28-ae-d2-a5″,”data”:”YAYAAAAABgABkOeYgwq4″,”datr”:50000,”deveui”:”00-80-00-00-04-00-1e-e7″,”fdev”:25000,”freq”:869.52499999999998,”imme”:true,”ipol”:true,”modu”:”FSK”,”ncrc”:false,”powe”:14,”rfch”:0,”size”:15}

output in xdot`

AT+DLC?
4

OK
AT+DLC?
5
OK

new data available
AT+RECV
0a01
OK

`

Thanks!

• This reply was modified 7 years, 8 months ago by alejandro ballesta.
• This reply was modified 7 years, 8 months ago by alejandro ballesta.

[Jason Reiss]

Your latest example does not show a step of 2.
What is the AT+RSSI of received packet?
Perhaps a packet was missed.
You could test with RX2 datarate to 5 or 6, FSK is not as robust as LoRa.

[alejandro ballesta]

yes you’re right. this time dlc was incremented just 1, maybe rx error.
I have just tried another one, same result. One received one not.

at+rssi
-61, -87, 0, -81
OK

As you said, I noticed data from the xdot is modu:LORA but frames from the Conduit are modu:FSK.

How can I change downlink modulation in the Conduit?

[Jason Reiss]

Use the Rx2 Datarate setting.

This setting will be sent to the dot in OTA join response.

[alejandro ballesta]

Hi Jason,

You’re right, it was the modulation. After copying the lora-network-server.conf.sample to /var/config/lora, some params were changed to setup for EU band but some not. Rx2Datarate old value was 8.

I’ve changed to values from 0 to 7 and the results now are really good.

Thank you very much!

[Author]

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