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Connected mode (commands)

Recommendation

To connect to the tag and download the datalogger, it is recommended to configure an Advertising Interval less than or equal to 3 seconds. If the advertising period is greater than this value, establishing the connected mode may take longer and may require several attempts.

Command list

CommandActionMinimum firmware version
LED_ONTurn ON the LED (infinite blinking)≥ 1.0.0
LED_OFFTurn OFF the LED≥ 1.0.0
LED_ON XXTurn ON the LED for XX seconds≥ 2.0.0
BUZZ_ONTurn ON the buzzer (repeated beeps)≥ 1.0.0
BUZZ_OFFTurn OFF the buzzer≥ 1.0.0
BUZZ_ON XXTurn ON the buzzer for XX seconds≥ 2.0.0
DIGI_ONSet digital output to ON≥ 2.1.0
DIGI_OFFSet digital output to OFF≥ 2.1.0
DIGI_ON XXSet digital output ON for XX seconds≥ 2.1.0
RAZ_COUNTReset counter≥ 2.0.0
LOG_DLDownload datalogger (chronological order)≥ 2.0.0
LOG_SO_DLDownload in reverse order≥ 4.0.0
LOG_RSTErase datalogger and timestamp≥ 2.0.0
LOG_SP_DL XX YYDownload values between index XX and YY (chronological)≥ 4.0.0
LOG_SP_INV_DL XX YYDownload values between index XX and YY (reverse)≥ 4.0.0
LOG_SP_DL_DATEDownload between dates (chronological)≥ 4.1.0
LOG_SP_INV_DL_DATEDownload between dates (reverse)≥ 4.1.0
LOG_SET_CURR_DATESet current tag date≥ 4.1.0
LOG_READ_CURR_DATERead current date≥ 4.1.0
LOG_READ_START_DATERead start recording date≥ 4.1.0
GET_BATT_VOLTAGEReturn battery voltage (mV)≥ 2.1.0
GET_SENSOR_DATAReturn last sensor value≥ 2.2.0

Simple data logger (relative time)

ELA Innovation sensor tags can use the datalogger feature.

The datalogger records data while advertising, with each value associated with a timestamp indicating when it was measured.

Operation​

For firmware versions < 4.0.0, the datalogger can be retrieved in connected mode using:

LOG_DL

Data format​

Example for a temperature sensor with a 30-second interval:

Temperature LOG:
DATA_START
0d0h0m30s:2712
0d0h1m0s:2730
0d0h1m30s:2695
…
1d3h25m30s:1505
END_OF_DATA
  • 0d0h0m30s → 30 seconds after startup
  • 1d3h25m30s → 1 day, 3h, 25 min, 30 sec after startup

General format:

xxd xxh xxm xxs : sensor value

Sensor values match those transmitted in advertising frames.

Data deletion​

Command:

LOG_RST

Deletes all datalogger content.

Partial download (firmware ≥ 4.0.0)​

Used to reduce the amount of transferred data.

Commands​

LOG_SP_DL XX YY

→ chronological order (XX = oldest)

LOG_SP_INV_DL XX YY

→ reverse order (XX = newest)

Examples​

LOG_DL​

DATA_START
0d0h0m30s:2712
...
END_OF_DATA

LOG_SP_DL 03 12​

DATA_START
0d0h1m30s:2695
...
END_OF_DATA

LOG_SP_INV_DL 03 12​

DATA_START
1d3h25m30s:1505
...
END_OF_DATA

Absolute time datalogger

For firmware versions strictly below 4.1.0, the datalogger timestamp can be retrieved in absolute time using the format:

DD/MM/YYYY HH:MM:SS Tz:Tz

with the command:

LOG_SP_DL_DATE

Operating principle​

Using absolute time requires setting a reference date in the beacon using:

LOG_SET_CURR_DATE

This command must be sent:

  • after the start of logging (after LOG_RST or device reboot)
  • before executing LOG_SP_DL_DATE

Partial download​

As with the simple datalogger, it is possible to download only part of the data by specifying a date range:

LOG_SP_DL_DATE DD/MM/YYYY HH:MM dd/mm/yyyy hh:mm

Reverse download​

It is also possible to retrieve data in reverse chronological order (newest first):

LOG_SP_INV_DL_DATE

A date range can also be specified.

Command examples​

LOG_DL​

Temperature LOG:
DATA_START
0d0h0m30s:2712
0d0h1m0s:2730
0d0h1m30s:2695
…
1d3h24m30s:1617
1d3h25m0s:1500
1d3h25m30s:1505
END_OF_DATA

LOG_SP_DL 03 12​

Temperature LOG:
DATA_START
0d0h1m30s:2695
0d0h2m0s:2700
0d0h2m30s:2705
…
0d0h5m0s:2902
0d0h5m30s:2875
0d0h6m0s:2822
END_OF_DATA

LOG_SP_INV_DL 03 12​

Temperature LOG:
DATA_START
1d3h25m30s:1505
1d3h25m0s:1500
1d3h24m30s:1617
…
1d3h20m30s:1200
1d3h20m00s:1102
1d3h19m30s:1015
END_OF_DATA

Data Logger EN12830

BLE connected mode configuration​

Start recording​

To begin storing temperature measurements in the tag memory, you must send the start date/time to the tag. This start date/time will be used as the reference for timestamping the data. After sending the command, the data logger will start monitoring and storing values for the period defined in the NFC configuration.

Command: DATALOGGER_START

You must then provide the BLE password so that the command is accepted by the tag. Finally, you must provide the date using the following format:

DD/MM/YYYY HH:mm:SS +hh:gg

Where:

  • DD: start day of the recording, written with 2 digits (e.g. 01, 08, 15...)
  • MM: start month of the recording, written with 2 digits (e.g. 01, 05, 11...)
  • YYYY: start year of the recording, written with 4 digits (e.g. 2019...)
  • HH: start hour of the recording in 24-hour format, written with 2 digits (e.g. 02, 16, 23...)
  • mm: start minute of the recording, written with 2 digits (e.g. 01, 26, 54...)
  • SS: start second of the recording, written with 2 digits (e.g. 05, 18, 56...)
  • hh: UTC timezone hour used to start the recording, written with 2 digits (e.g. 00, 03...)
  • gg: UTC timezone minutes used to start the recording, written with 2 digits (e.g. 00, 30...)

Command example:

DATALOGGER_START PASSWORD_1 05/06/2019 11:20:00 +01:00

Tag responses:

  • If the password is valid: DATALOGGER_START: Success
  • If the password is invalid: DATALOGGER_START: ACCESS DENIED
  • If the date is invalid: DATALOGGER_START: WRONG PARAMETERS
Important

When this command is sent to the tag, all previously stored content in the data logger is deleted and the recording restarts from zero.

When this command is sent to the tag, the first sensor measurement will be performed after the logging period defined in the NFC configuration.

For example, if the Datalogger period is 30 seconds, the first data entry will be measured and stored 30 seconds after the DATALOGGER_START command is sent.

Stop recording​

You can stop the recording on the tag using the DATALOGGER_STOP command. The BLE password must be provided for the command to be accepted by the tag. Data already recorded will not be erased by this command.

Command example:

DATALOGGER_STOP PASSWORD_1

Tag responses:

  • If the password is valid and recording is running: DATALOGGER_STOP: Success
  • If the password is valid but recording is not running: DATALOGGER_STOP: LOG not started!
  • If the password is invalid: DATALOGGER_STOP: ACCESS DENIED

The data stored in the data logger memory can be retrieved using the READ_DATA command until another recording session is started or the tag is rebooted.

Data retrieval and verification​

Reading all data logger values​

Important

You can read the stored data at any time without stopping the recording.

Four commands in connected mode are available to retrieve data from the data logger:

  1. READ_DATA: downloads the complete data logger in chronological order (oldest to newest)
  2. READ_INV_DATA: downloads the complete data logger in reverse order (newest to oldest)
  3. READ_SP_DATA DD/MM/YYYY HH:MM dd/mm/yyyy hh:mm: downloads the complete data logger in chronological order between the specified dates
  4. READ_SP_INV_DATA DD/MM/YYYY HH:MM dd/mm/yyyy hh:mm: downloads the complete data logger in reverse chronological order between the specified dates

For each command, the password must be specified. If the command syntax is valid, the tag returns READ_DATA: Success. The tag then starts transmitting its data.

Command examples:

READ_DATA PASSWORD_1
READ_INV_DATA PASSWORD_1
READ_SP_DATA DD/MM/YYYY HH:MM dd/mm/yyyy hh:mm PASSWORD_1
READ_SP_INV_DATA DD/MM/YYYY HH:MM dd/mm/yyyy hh:mm PASSWORD_1

Tag responses:

  • If the password is valid: READ_DATA: Success
  • If the password is invalid: READ_DATA: ACCESS DENIED
  • If the password is valid but recording has not started: READ_DATA: LOG not started!

Once the command is received, the tag transmits all data stored in the data logger memory. The data is formatted as follows:

---DOWNLOAD_START---
Firmware version: 2.1.0\n
MacAddress: 01:02:03:04:05:FE\n
Name: TAG_LOCAL_NAME\n
Unit: Celsius degrees\n
Start date: 01/04/2019 11:26:33 +01:00\n
<DATA_START>\n
01/04/2019 11:26:33+01:00: 23.34\n
01/04/2019 11:26:43+01:00: 23.44\n
[…]
<DATA_END>\n
CRC16: 0x0D06\n
---DOWNLOAD_END---
Note

New line characters (\n) are not visible but must be taken into account when calculating the CRC.

Field description:

  • ---DOWNLOAD_START---: marker indicating the beginning of the transmission from the data logger
  • Firmware version: firmware version of the data logger (tag)
  • MacAddress: unique identifier of the tag
  • Name: tag name as configured in the NFC memory
  • Unit: unit used for the temperature values (°C in this example)
  • Start date: start of recording as sent by the DATALOGGER_START command
  • <DATA_START>: marker indicating the beginning of temperature data transmission
  • 01/04/2019 11:26:33+01:00: 23.34: example of timestamped temperature data
  • <DATA_END>: marker indicating the end of temperature data transmission
  • CRC16: cyclic redundancy check calculated from the transmitted data
  • ---DOWNLOAD_END---: marker indicating the end of the transmission from the data logger

Reading temperature data​

In the previous example, temperature readings are formatted as follows:

01/04/2019 11:26:33+01:00: 23.34
  • 01/04/2019 corresponds to the date the temperature was measured
  • 11:26:33 corresponds to the time the temperature was measured
  • +01:00 corresponds to the UTC timezone provided with the DATALOGGER_START command
  • 23.34 corresponds to the temperature value expressed in the unit transmitted by the data logger (23.34°C in this example)

Data logger CRC verification​

The data logger data is verified using a CRC16 (Cyclic Redundancy Check) calculation.

CRC parameters:

  • Algorithm: CRC-16-CCITT
  • Polynomial: 0x1021
  • Initialization value: 0xFFFF

Example calculation

Input data (ASCII type):

0123456789ABCDEF

Result:

0x2C1F

The CRC calculation is performed on all data between the marker ---DOWNLOAD_START--- (not included) and the string CRC16: 0x (included).

Complete data logger example:

---DOWNLOAD_START---
Firmware version: 2.1.0\n
MacAddress: FA:FD:50:39:A1:2C\n
Name: BE_TEST_T3\n
Unit: Celsius degrees\n
Start date: 14/06/2019 12:00:00 +01:00\n
<DATA_START>\n
14/06/2019 12:00:10 +01:00: 26.62\n
14/06/2019 12:00:20 +01:00: 26.62\n
<DATA_END>\n
CRC16: 0xDF91\n
---DOWNLOAD_END---

The CRC value is calculated using all the data displayed above (from Firmware version to CRC16: 0x included). In this example, the value is therefore 0xDF91.

An online CRC calculator is available at:
http://www.tahapaksu.com/crc/

Use the result from the CRC-CCITT (0xFFFF) field.

Important
  • Using the READ_DATA function does not erase the recorded and transmitted data
  • Recording is stopped during transmission (until the marker ---DOWNLOAD_END---) and automatically resumes once the transmission is finished

Reading the recording start date​

The command used to read the start date sent to the tag is READ_START_DATE. The BLE password must be provided for the command to be accepted.

Command example:

READ_START_DATE PASSWORD_1

Tag responses:

  • If the password is valid but recording has not started: READ_START_DATE: LOG not started!
  • If the password is valid and recording is running: READ_START_DATE: DD/MM/YYYY HH:MM:SS +UU:UU
  • If the password is invalid: READ_START_DATE: ACCESS DENIED