You are right. This is exactly how it is currently implemented. The NB-IoT CoT access is currently only a test product and thus the behavior of the alarm is not scheduled to change anytime soon. I will forward your request to our internal team for further discussions.
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RE: Only one alarm can be sent
Only one alarm can be sent
I am working on a device which connects to the CoT and I don’t understand how alarms work. I thought that I can register all 4 severities of alarms and then, when something occurs, I will send some string about what happened to the one which is appropriate.
When I send the first alarm, everything works out fine. But when I send another one it gets counted as an occurrence of the first one. Regardless of the severity, regardless of the message. This happens until the first alarm is marked as resolved.
Should I do something different to be able to send more then one alarm till user input?
Thank you for any advice
RE: NB IoT Connector & Protocol MQTT-SN
MQTT-SN is a protocol for data transmission (specification available here:
It works in the publish/subscribe manner. A device which wants to send data to CoT, needs to have implemented this protocol. The easiest way to implement is to use the Open Source Paho Client from von Eclipse.
CoT can only be addressed over the REST interface and therefore the connector is needed to convert incoming MQTT-SN messages to CoT messages.
There is a second important function of the connector. It interprets data, so for example temperature can be identified as such. Prerequisite for that is that MQTT-SN messages are being formatted according a predefined convention. How this is to be accomplished is described in the NBIOT-Protocol-Developerguide.
If MQTT-SN messages are correctly formatted and compliant to the convention described in the developerguide, then data is transferred into the Cloud of Things.
The mentioned IP address belongs to a private network, since it is the tunnel endpoint of the IPSec-tunnel from private APN of the CoT. This server is only acceible via the private APN.
For sending UDP packets to a server residing in the Internet, you need to have SIM cards with public APN (internet.nbiot.telekom.de). Since you have ordered only SIM cards for CoT, you are only able to send data to the CoT with IP 172.25.102.151:1883
NB IoT Connector & Protocol MQTT-SN
The “NB IoT Protocol Developerguide” is mentioning the “NB-IoT-Connector” and “NBIoT Protocol MQTT-SN”. As I understood, these are mandatory for sending data to the cloud. What is this Connector and why is it needed? Is it possible to send UDP packtes to our own server with a public Internet address?
RE: No connection with Cloud of Things
First of all, before sending any data we need to open a socket with the command
Afterwards, IMSI and PW need to be converted into the hexstring format. This means the
IMSI(ascii) = 012345678912345
IMSI(hexstring) = 303132333435363738393132333435
and the password
PW(ascii) = abcdefgh
PW(hexstring) = 6162636465666768
putting these values into the AT+NSOST command yields:
This means the hexstring version of payload has twice as many symbols
(58) as specified in the number of bytes transferred (29).
I hope that we this guidance everything will be fine.
No connection with Cloud of Things
My device stays always into an inactive Status on the Cloud (Connection not monitored and push Connection are both inactive) even if a Connection with the Cloud of Things Gateway was stablished. I have followed the “Beispielsession NB-IoT Access und cloud der Dinge” and I´ve received the notification (030500) from the Gateway.
How could I change this status on the cloud and receive any data from my device?
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