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Consider a table like this.
Number of events since last counter update message transmission | Elapsed time since last counter update message transmission |
|---|---|
0 | 1200 |
1 | 300 |
2 | 200 |
5 | 100 |
10 | 60 |
The table describes a threshold in 2D space that defines if a counter update message must be sent. If a point lies left from the curve the message must be sent.
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the minimum period between messages. In this case, it is 60 seconds and no matter how many cars passed after the last message a new message will be sent not earlier than 60 seconds after the last message.
the minimum number of events necessary to send the next message. In this case, it is 0, and even if there were no new passing cars after the last message the new one will be sent in 1200 seconds after the last message.
Another example.
Number of events since last counter update message transmission | Elapsed time since last counter update message transmission |
|---|---|
2 | 200 |
5 | 100 |
10 | 60 |
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Here the minimum number of new events is 2, so if after the last message there were none or only 1 event there will be no new counter update message ever.
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Here is a table showing the expected lifespan in years of the device vs the number of messages per day and configured data rate(or actual data rate in case of ADR enabled).
Data rate\Number of messages per day | 10 | 20 | 50 | 100 | 200 | 500 |
DR0(SF12) | 7.4 | 7.2 | 6.6 | 5.9 | 4.8 | 3.1 |
DR1(SF11) | 7.5 | 7.4 | 7.0 | 6.5 | 5.7 | 4.2 |
DR2(SF10) | 7.5 | 7.5 | 7.3 | 7.0 | 6.5 | 5.4 |
DR3(SF9) | 7.6 | 7.5 | 7.5 | 7.3 | 7.0 | 6.3 |
DR4(SF8) | 7.6 | 7.6 | 7.5 | 7.4 | 7.3 | 6.8 |
DR5(SF7) | 7.6 | 7.6 | 7.6 | 7.5 | 7.4 | 7.2 |
4.2 Uplink messages
Uplink messages are those sent from the sensor to the network.
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Counter update message uses port 1 and is not confirmed with 0 repetitions by default. It may be configured as confirmed or unconfirmed with repetitions (see downlink messages).
Byte | Name |
|---|---|
0 | Counter value - |
bits 15..8 | |
1 | Counter value - |
bits 7..0 |
Only 16 least significant bits of the counter are sent in this message, the server must take care of possible overflows. It is also important to notice, that counter information is not stored in nonvolatile memory and so it is lost in case of reboot and the counter resets to 0. The server can correctly process reboot by processing the Startup message(if Reset cause is not equal to 0, there was reboot and the counter was reset to 0).
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The heartbeat message uses port 2 and it is always confirmed. The heartbeat message is sent every 24 hours (by default).
Byte | Bits | Name |
|---|---|---|
0 | 4..0 | Error Mask |
7..5 | Reserved | |
1 | 7..0 | Battery voltage - the last value |
2 | 7..0 | Battery voltage - the mean value(last 24 hours) |
Heartbeat messages allow the device’s health monitoring using Error Mask, where all zeros values which are not hardware issues were detected.
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The startup message uses port 3 and it is always confirmed. It will be sent after every startup/reboot /(re-)join event:
Byte | Name |
|---|---|
0 | Major part of version number |
1 | Minor part of version number |
2 | Micro part of version number |
3 | Reset cause 0x00 No reset ( Startup message after re-joining LoRaWAN network) 0x01: Watchdog reset 0x02: Power On Reset 0x03: User Request Reset 0x06 - Brownout Reset 0x07 - Others |
4.2.4 Debug messages
The Debug messages use port 6 and they are always unconfirmed. By default, these messages are enabled and have no repetitions, but they may be disabled or increased by the number of repetitions used (see downlink messages). These messages do not have a fixed length as their payload depends on the type of debug message.
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DataRate configuration uses port 52. The default value is DR2 (0x02) The selected configuration is persistent unless overwritten in the join procedure. Higher DataRates increases the battery lifetime of the sensor but may reduce the reliability of the reception of messages by the Gateway. This is especially the case for unconfirmed messages.
Byte | Bits | Name | Default value |
|---|---|---|---|
0 | 0..2 | DataRate configuration | 2 (DR2) |
3 | Enable ADR(Adaptive Data Rate):
| 0 | |
4..6 | Counter update confirmation configuration | 1(Unconfirmed with 1 uplink message(0 repetitions)) | |
7 | Reserved | 0 |
DataRate configuration value | DataRate(Spreading Factor) |
|---|---|
0 | DR0 (SF12) |
1 | DR1 (SF11) |
2 | DR2 (SF10) |
3 | DR3 (SF9) |
4 | DR4 (SF8) |
5 | DR5 (SF7) |
6 | Reserved |
7 | Reserved |
Counter update confirmation configuration | Description |
|---|---|
0 | Confirmed(up to 8 repetitions) |
1 | Unconfirmed with 1 uplink message(0 repetitions) |
2 | Unconfirmed with 2 uplink messages(up to 1 repetition) |
3 | Unconfirmed with 3 uplink messages(up to 2 repetitions) |
4 | Unconfirmed with 4 uplink messages(up to 3 repetitions) |
4.3.2 Update transmission threshold configuration
Update transmission threshold configuration uses port 53. The configuration selected is persistent. The configuration is a table where every record represents a point of the counter update threshold curve. If elapsed time of a record is equal to 0xFFF, this record is not used.
Byte | Bits | Name |
|---|---|---|
0 | 4..7 | Record 1 - Number of events |
3..0 | Record 1 - Elapsed time, seconds(bits 11..8) | |
1 | 7..0 | Record 1 - Elapsed time, seconds(bits 7..0) |
2 | 4..7 | Record 2 - Number of events |
3..0 | Record 2 - Elapsed time, seconds(bits 11..8) | |
3 | 7..0 | Record 2 - Elapsed time, seconds(bits 7..0) |
4 | 4..7 | Record 3 - Number of events |
3..0 | Record 3 - Elapsed time, seconds(bits 11..8) | |
5 | 7..0 | Record 3 - Elapsed time, seconds(bits 7..0) |
6 | 4..7 | Record 4 - Number of events |
3..0 | Record 4 - Elapsed time, seconds(bits 11..8) | |
7 | 7..0 | Record 4 - Elapsed time, seconds(bits 7..0) |
8 | 4..7 | Record 5 - Number of events |
3..0 | Record 5 - Elapsed time, seconds(bits 11..8) | |
9 | 7..0 | Record 5 - Elapsed time, seconds(bits 7..0) |
The default counter update message transmission policy table described below.
Number of events since last counter update message transmission | Elapsed time since last counter update message transmission, seconds |
|---|---|
0 | 3600 |
1 | 60 |
2 | 40 |
X | 0xFFF - not used |
X | 0xFFF - not used |
There is also a feature that allows you to set only used(defined) records of the policy table. So, for example, if you send just 2 bytes they will be interpreted as 1 record of the table and other records will be set as not used.
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Heartbeat frequency uses port 55. The default value is 23 what is equal to 24 hours. The configuration selected is persistent.
Byte | Name |
|---|---|
0 | Heartbeat interval configuration Interval = (value+1)hours |
4.3.4 Debug configuration
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Heartbeat NACK limit configuration uses port 72 and is used to specify how many heartbeat messages may be unacknowledged without initiating re-join procedure. The selected configuration is persistent. Default value is 3. 15 (0xF) and it is a special value that disables re-join functionality completely
Byte | Bits | Name | Default value |
|---|---|---|---|
0 | 0..3 | Heartbeat NACK limit | 3 |
4..7 | Reserved | 0 |
4.3.6 Command
Command uses port 71 and it is used to initiate different commands mainly for debugging.
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