Sample Implementations

Lobaro Pressure or Lobaro Pressure and Temperature Sensor

Lobaro Platform Device Type: lobaro-pegelsonde-hybrid


Select the correct sensor by checking the cable flag. The Pressure and Temperature sensor got a "P+T" marking.

Lobaro Pressure and Temperature SensorLobaro Pressure Sensor

KELLER Series 26X

Lobaro article: #3000625Lobaro article: #3000588 (discontinued)Lobaro article: #3000701

  • 0 - 15 mH2O (other lengths on request)
  • Accuracy: +/- 0.25% FSO (Fully Scale Output)
  • Drift: +/- 0.3% FSO per year 
  • 0 - 15 mH2O
  • Accuracy: 0.5% +/- FSO (Fully Scale Output)
  • Drift: +/- 0.3% FSO per year 

Keller Website

White=GND Black =+Vcc

Blue=RS485+ Yellow=RS485-



Lobaro Pressure and Temperature Sensor

To read out the pressure & temperature probe, the Hybrid Modbus Gateway must be configured as follows:

ParameterValueComment
WANlorawanFor LoRaWAN OTAA usage.
PlFmt5Sets the payload to a short format.
MbCmd0 0/5 * * * *:R,9600,8N1:010300160002,010300260002,fa0400050001
  • 010300160002 - Read register 22-23 (pressure)
  • 010300260002 - Read register 38-39 (temperature)
  • FA0400050001 - Read internal register 5 (vBat)

The CRON Expressions can be adjusted to set time of sensor reading.

PowerOnDelay3000Battery variant only. Sets time (in ms) between activating sensor power and reading value (time for sensor to be ready).

Modbus Register Mapping

The probe is a Modbus slave with the following registers:

Modbus Command: <Slave Address (1)><Function (1)><Address (2)><Length (2)>

  • Length = Register count -> 1 Register = 2 Bytes
  • Function

    • 0x03 = Read Holding Register
    • 0x04 = Read Input Register
    • 0x06 = Write Holding Register


AddressFunctionBytesData ScopeDescription
0x00000x03, 0x0621-255Slave Address
0x00010x03, 0x062
  • 0-1200
  • 1-2400
  • 2-4800
  • 3-9600
  • 4-19200
  • 5-38400
  • 6-57600
  • 7-115200
Baud rate
0x00020x03, 0x062
  • 0 -No 
  • 1- Odd 
  • 2 - Even 
  • No check
  • Odd check
  • Even check
0x00030x032
  • 0- kpa
  • 1- Mpa
  • 2- ma
  • 3- %
  • 4- Inh2o
  • 5- FtH2o
  • 6- mmH2o
  • 7- mmHg
  • 8- psi
  • 9- bar
  • 10- mBar
  • 11- g/cm²
  • 12- kg/cm²
  • 13- Pa
  • 14- Torr
  • 15- Atm
  • 16- Null
  • 17- M
  • 18- cm
  • 19- mm
  • 20-InHg
  • 21- mHg
  • 22- MH20
  • 23- °C

Pressure unit 

 0x0004

0x032
  • 0 -####
  • 1- ###.#
  • 2 - ##.##
  • 3 - #.###
  • 4 - #.####

Decimal point stands for 0-4 digits
decimal points

0x00050x0320-30Filtering Coefficient
0x0016-00170x0344 byte float

Measurement Pressure output value

0x0018-00190x03, 0x0644 byte floatMaster variable of Pressure offset

0x001A-001B

0x0344 byte floatRange minimum of Pressure Transmitter
0x001C-001D0x0344 byte floatRange maximum of Pressure Transmitter
0x001E-001F0x0344 byte floatRange minimum of Pressure Sensor
0x0020-00210x0344 byte floatRange maximum of Pressure Sensor
0x0026-00270x0344 byte floatMeasurement Temperature output value
0x00A6-00A70x0644 byte floatZero Clearing value of Pressure Transmitter
0xFFFF0x062
  • 0 - save to user area
Save data to user area
0xFFFC0x062
  • 0 - factory reset
Restore to factory status (user settings and calibration data)


Data Uplink (Port 20)

Bytes | 0 .    | 1 . 2 . 3 . 4 . | 5 . 6 . 7 . 8 . | 9 . 10 . |
------+--------+-----------------+-----------------+----------+
Field | Header | Pressure        | Temperature     | Voltage  |


All values are encoded big-endian

FieldTypeValue
Headeruint80x00 on success, 0x80 if an error occurred
Pressurefloat32Pressure in mH2O, ffffffff on error.
Temperaturefloat32

Temperature in °C, ffffffff on error.

Voltageuint16Voltage in mV, ffff on error

010300160002

Example

# Example of a successful measurement
'003d94ce4541b7a5120e2a'
  '00'       -> Successful readout
  '3d94ce45' -> 0.073 mH2O
  '41b7a512' -> 22.96 °C
  '0e2a'     -> 3626 mV / 3.626 V

# Example
'80ffffffffffffffff'
  '80'       -> An error occurred.
  'ffffffff' -> Pressure could not be read.
  'ffffffff' -> Temperature could not be read.
  'ffff'     -> Voltage could not be read.

Reference Parser

see below

Lobaro Pressure Sensor

Reading from the Lobaro Pressure Sensor using the Hybrid Gateway can be done by setting the following parameters in the configuration:

ParameterValueComment
WANlorawanFor LoRaWAN OTAA usage.
PlFmt5Sets the payload to a short format.
MbCmd0 0/5 * * * *:R,9600,8N1:010300040001,fa0400040001,fa0400050001
  • 010300040001 - Read register 4 (pressure)
  • fa0400040001 - Read internal register 4 (temperature in box)
  • fa0400050001 - Read internal register 5 (vBat)

The CRON Expressions can be adjusted to set time of sensor reading.

PowerOnDelay3000Battery variant only. Sets time (in ms) between activating sensor power and reading value (time for sensor to be ready).

Modbus Register Mapping

The probe is a Modbus slave with the following registers:

Modbus Command: <Slave Address (1)><Function (1)><Address (2)><Length (2)>

  • Length = Register count -> 1 Register = 2 Bytes
  • Function

    • 0x03 = Read Holding Register
    • 0x06 = Write Holding Register
AddressFunctionBytesData ScopeDescription
0x00000x03, 0x0621-255Slave Address
0x00010x03, 0x062
  • 0-1200
  • 1-2400
  • 2-4800
  • 3-9600
  • 4-19200
  • 5-38400
  • 6-57600
  • 7-115200
Baud rate
0x00030x032
  • 0 -####
  • 1- ###.#
  • 2 - ##.##
  • 3 - #.###

Decimal point stands for 0-3 digits
decimal points


0x00020x032
  • 0- Mpa/
  • 1- Kpa
  • 2- Pa
  • 3- Bar
  • 4- Mbar
  • 5- kg/cm2
  • 6- psi
  • 7- mh2o
  • 8- mmh2o

Pressure unit

0x00040x032-32768-32767Measurement output value
0x00050x032-32768-32767Zero point of transmitter range
0x00060x032-32768-32767Full point of transmitter range
0x000c0x03, 0x062-32768-32767Zero point offset value, generally factory sets as 0
0x000F0x062
  • 0 - save to user area

0x00100x062
  • 1 - factory reset


Data Uplink LoRaWAN (Port 20)

Bytes | 0 .    | 1 . 2 .  | 3 . 4 .     | 5 . 6 . |
------+--------+----------+-------------+---------|
Field | Header | Pressure | Temperature | Voltage |


All values are encoded big-endian

FieldTypeValue
Headeruint80x00 on success, 0x80 if an error occurred
Pressureint16BE

Pressure in mmH2O

Temperatureint16BE Temperature in °C inside Bridge
Voltageuint16BE Voltage in mV, ffff on error

Example

# Example of a successful measurement
'000211001a0e2a'
  '00'           -> Successful readout
  '0211' -> 529  -> 0.529 mH2O
  '001a' -> 26   -> 26°C (inside Box)
  '0e2a' -> 3626 -> 3626 mV / 3.626 V

Keller PR26X

Configuration

Connected pressure sensor probe from Keller Druckmesstechnik PR26X series.


ParameterValueComment
WANlorawanFor LoRaWAN OTAA usage.
PlFmt5Sets the payload to a short format.
MbCmd0 0 * * * *:R,9600,8N1:010300020002,010300080002,FA0400050001Reads four Registers: 2 + 3 (Float, Pressure in Bar) and 8 + 9 (Float, Probe Temperature) + Device battery voltage
PowerOnDelay1500Battery variant only. Sets time (in ms) between activating sensor power and reading value (time for sensor to be ready).

Example Modbus response

Hex to float converter: https://gregstoll.com/~gregstoll/floattohex/

Pressure (0x3f75f07b):

Temperature (0x41b5c079):

Data Uplink (Port 20)

Bytes | 0 .    | 1 . 2 . 3 . 4 . | 5 . 6 . 7 . 8 . | 9 . 10 . |
------+--------+-----------------+-----------------+----------+
Field | Header | Pressure        | Temperature     | Voltage  |


All values are encoded big-endian

FieldTypeValue
Headeruint80x00 on success, 0x80 if an error occurred
Pressurefloat32Pressure in Bar, ffffffff on error.
Temperaturefloat32

Temperature in °C, ffffffff on error.

Voltageuint16Voltage in mV, ffff on error

Reference Parser (All variants)

Pressure Probe Parser
/**
 * Parser for Lobaro Pressure Probe via LoRaWAN (hybrid gateway).
 * Usable for Pressure Probe as or with Presure+Temperature Probe.
 * Works with TTN, ChirpStack, or the Lobaro Platform.
 */
function signed(val, bits) {
    // max positive value possible for signed int with bits:
    var mx = Math.pow(2, bits-1);
    if (val < mx) {
        // is positive value, just return
        return val;
    } else {
        // is negative value, convert to neg:
        return val - (2 * mx);
    }
}
function int16_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return signed(bytes[0] << 8 | bytes[1] << 0, 2*8);
}
function uint16_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return bytes[0] << 8 | bytes[1] << 0;
}
function uint32_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3] << 0;
}
function float32FromInt(asInt) {
    var sign = (asInt >> 31) == 0 ? 1 : -1;
    var exponent = ((asInt >> 23) & 0xFF) - 127;
    var significand = (asInt & ~(-1 << 23));
    if (exponent === 128)
        return null;
        // return sign * ((significand) ? Number.NaN : Number.POSITIVE_INFINITY);
    if (exponent === -127) {
        if (significand === 0) return sign * 0.0;
        exponent = -126;
        significand /= (1 << 22);
    } else {
        significand = (significand | (1 << 23)) / (1 << 23);
    }
    return sign * significand * Math.pow(2, exponent);
}
function float32_BE(bytes, idx) { return float32FromInt(uint32_BE(bytes, idx)); }
 
/**
 * TTN decoder function.
 */
function Decoder(bytes, port) {
    var vals = {};
    if( port == 20 ){
        if (bytes.length==5) {
            // Pressure Probe without temperature sensor and Bridges internal Temperature
            vals["error"] = !!(bytes[0]&0x80);
            vals["pressure"] = int16_BE(bytes, 1)/1000;
            vals["temperature"] = int16_BE(bytes, 3);
        }  else if (bytes.length==7) {
            vals["error"] = !!(bytes[0]&0x80);
            vals["pressure"] = int16_BE(bytes, 1)/1000;
            vals["temperature"] = int16_BE(bytes, 3);
            vals["voltage"] = uint16_BE(bytes, 5) / 1000;
        } else if (bytes.length==9) {
            vals["error"] = !!(bytes[0]&0x80);
            // pressure in mH2O
            vals["pressure"] = float32_BE(bytes, 1);
            // temperature in Degree Celsius
            vals["temperature"] = float32_BE(bytes, 5);
        } else if (bytes.length==11) {
            vals["error"] = !!(bytes[0]&0x80);
            // pressure in mH2O
            vals["pressure"] = float32_BE(bytes, 1);
            // temperature in Degree Celsius
            vals["temperature"] = float32_BE(bytes, 5);
            vals["voltage"] = uint16_BE(bytes, 9) / 1000;
        }
    }
    
    if (port === 64 && bytes.length == 13) { // status packet
        vals["Firmware Identifier"] =  String.fromCharCode(bytes[0]) + String.fromCharCode(bytes[1]) + String.fromCharCode(bytes[2]);
        vals["FirmwareVersion"] = bytes[3] + '.' + bytes[4] + '.' + bytes[5]; 
        vals["status"] = bytes[6]; 
        vals["reboot reason"] = bytes[7];
        vals["final words"] = bytes[8];
        vals["voltage"] = uint16_BE(bytes,9)/1000.0
        vals["temperature"] =  int16_BE(bytes,11)/10.0;
    } 
    return vals;
}
  
/**
 * TTN V3 Wrapper
 */
function decodeUplink(input) {
   return {
    data: {
      values: Decoder(input.bytes, input.fPort)
    },
    warnings: [],
    errors: []
  };
}
  
/**
 * ChirpStack decoder function.
 */
function Decode(fPort, bytes) {
    // wrap TTN Decoder:
    return Decoder(bytes, fPort);
}
  
/**
 * Lobaro Platform decoder function.
 */
function Parse(input) {
    var data = bytes(atob(input.data));
    var port = input.fPort;
    return Decoder(data, port);
}