sending data from mDot module to Conduit gateway

[Michal]

Hi,

while trying to program mDot module using mDot lib I’ve met some problems with sending/receiving data to/from Conduit gateway.

On gateway there is a Node-RED PingPong implementation. mDot module connects to gateway and starts to send few bytes messages and such messages are sent back to mDot module by gateway. After few loops gateway stops to provide “pong” response.
And here are few cases:
– mDot messages are visible in Node-RED while sniffing Lora receiver block but responses are not received by mDot
– mDot sent messages, they are not visible in NodeRed and in lora logs warnings are present eg. “9:23:43:163|WARNING| LoRa::ReceivedFrame::MessageRejectException : Unexpected message type”

Any ideas what could be wrong? Of course mDot software is written in that way that starts to read response after message is sent.

[Michal]

I will add that I’m using latest mDot lib version.
Problem is also visible with AT commands SW version.

While there is problem with data transmission such description of error is present after command send “Operation Timed Out ACK not received”. Any idea why mDot module cannot receive message?

• This reply was modified 8 years, 9 months ago by Michal.

[Brandon Bayer]

Michal,

1) Are you using the 916 or 868 Mhz band?

2) Are you receiving some packets on the mDot or none at all?

3) Which version of the mbed library are you using? Make sure you are using rev 5. You can’t use rev 6 (the latest) without AEP version 1.0.30 which hasn’t been released yet.

4) When are you getting the MessageRejectException? Can you post all of the lora log output that contains this error?

5) Post your Node-RED flow (in Node-RED menu, click Export > Clipboard, then copy and paste it here.

-Brandon

[John C]

Any update on this? I see a similar issue here.

[Brandon Bayer]

John,

Can you describe exactly the behavior you are seeing and what you expect?

-Brandon

[John C]

Hi Brandon,

I have a mdot and conduit gateway. I am able to
1. I am able to get mdot sending data to Conduit gateway
2. The data i sent from mdot device is visible on node-red

What I am facing:
1. I have only 26% success rate of sending data from mdot to conduit. The rest I get an error “-5: Operation Timed Out”.
I see almost all the time the remaining 74% data on node-red but the device is unable to receive the ACK.
2. I used to see a higher percentage 60% success rate but now its in late 20 or early 30%. Dont know what has changed here.

To help you i have dumped the stats here:
Total Payload sent : 50
Payload sent failed: 37
Average: 26%
RSSI info (dB): last= -82, min= -83, max= -73, avg= -80
SNR info (dB): last= 26, min= 24, max= 31, avg= 26
TX power (dB): 20
UP = 52, Down= 14, Joins= 1, JoinFails= 0, MissedAcks= 38
Channels used: 868 MHz 868 MHz 868 MHz 869 MHz 869 MHz 869 MHz 869 MHz 869 MHz 869 MHz

Let me know if you need any further info.

Thanks,
John

[Brandon Bayer]

John,

Thanks for the helpful information. Please do the following test:

1) Place Conduit & mDot right beside each other
2) Take antennas off mDot & Conduit
3) Set Conduit tx power to 26
4) Set mDot tx power to 20
5) Have mDot join network
6) On mDot issue, AT+PING then AT+RSSI and post the output of these two commands.

-Brandon

[John C]

I am using the mdot library? Is it ok if I call the API exposed by this lib?

Thanks,
John

[John C]

Also another point regarding JOIN message. I have the following code (removed the check for errrors).

dot->setJoinRetries(255);

// attempt to join the network
pc.printf(“joining network\r\n”);

while ((ret = dot->joinNetwork()) != mDot::MDOT_OK) {
// in the 868 (EU) frequency band, we need to wait until another channel is available before transmitting again
wait_ms(dot->getNextTxMs() + 1);
}

Do we need the while loop here when we setJoinRetries. Also when I see that JOIN fails with “-4: Join Error” it is never able to JOIN back with the delay using while loop .

Thanks,
John

[Brandon Bayer]

John,

Please load the AT Command Firmware on the mDot for the test (available from the downloads page).

The delay in the while loop should not negatively affect the join.

-Brandon

[John C]

Using mdot library:

Total Payload sent : 10
Payload sent failed: 7
Average: 30%
Ping status: 0, RSSI= -115, SNR= -28
RSSI info (dB): last= -112, min= -114, max= -112, avg= -114
SNR info (dB): last= 17, min= 16, max= 18, avg= 16
TX power (dB): 20
UP = 12, Down= 5, Joins= 1, JoinFails= 0, MissedAcks= 8
Channels used: 868 MHz 868 MHz 868 MHz 869 MHz 869 MHz 869 MHz 869 MHz 869 MHz 869 MHz

Using
ATI
MultiTech mDot
Firmware: 0.1.4
Library : 0.0.9

AT+RSSI
-112, -112, -112, -112

OK
AT+PING
-118,-3.0

[Brandon Bayer]

John,

Please issue AT+PING before AT+RSSI. The order is important.

-Brandon

[John C]

AT+JOIN
Successfully joined network

OK
AT+PING
-119,-5.5

OK
AT+RSSI
-124, -125, -124, -125

[Brandon Bayer]

John,

I’m wondering if you have a defective MTAC-LORA card. Early production ones had a solder issue that’s since been fixed.

When did you get your MTAC-LORA? What is it’s serial number (visible on the Conduit’s homepage dashboard)?

-Brandon

[John C]

The serial number is 18253567 and got it around first week of Oct. Can this be replaced if its one of the early production ones?

Thanks,
John

[Brandon Bayer]

John,

Ok, it’s a really good chance your MTAC-LORA is defective and causing at least some of your issues. Also, there is a small bug in Conduit firmware 1.0.33 that can create problems for receiving data over 868 (this will be fixed in the next release).

To get it replaced for free, open a support case and include the following:
1) Your name
2) Your company
3) Return address
4) Contact phone number
5) MTAC-LORA serial number

-Brandon

[John C]

Ok i have raised a support case 5065580.

Meanwhile, are we sure that the LoRa mtdot card is not defective? Since every data sent from device seems to reach the gateway ( as per node-red debug message), its the ACK that is not received by the end device. Is there a known defect in the transmit side on MTAC-LORA?

Is there a different way I can have a chat, send a private message or email?

Thanks,
John

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