Sensor Output

$ANB, CRC, Date/Time, pH, Temp, Salinity, Specific Conductivity, Transducer Health, Sensor Diagnostics, Actual Conductivity, 0, File Number,

Parameter	Description
$ANB	ANB Sensors messsage identifier
CRC	CRC-16/Modbus 4 digit hex number
TIMESTAMP	Sample timestamp yyyy:mm:dd:hh:mm:ss
PH	Sample pH value (pH) (2 decimal places)
TEMP	Sample temperature (°C) (2 decimal places)
SALINITY	Sample salinity (ppt - parts per thousand) (2 decimal places)
SPECIFIC CONDUCTIVITY	Sample conductivity (mS/cm) (2 decimal places) Conductivity is calculated to 25C using this converter
TRANSDUCER HEALTH	Transducer health status code (0 to 8) see below for further information
SENSOR DIAGNOSTICS	Sensor health status code (0 to 3) see below for further information
ACTUAL CONDUCTIVITY	Sample conductivity (mS/cm) (2 decimal places)
RESERVED	currently 0
FILE NUMBER	the measurement data file number

All output as ASCII

Measurement Timings

- communication during sleep

Terminal Mode: When the sensor is in interval sleep, it does not respond to commands. To communicate with the sensor, you must first send the wake command.
Modbus Mode: Communication remains available during interval sleep. However, the sensor will return the last recorded measurement.

CRC

The C function for calculating the CRC value is:

// Compute the Modbus RTU CRC
UInt16 ModRTU_CRC(byte[] buf, int len)
{
  UInt16 crc = 0xFFFF;
  
  for (int pos = 0; pos < len; pos++) {
    crc ^= (UInt16)buf[pos];          // XOR byte into least sig. byte of crc
  
    for (int i = 8; i != 0; i--) {    // Loop over each bit
      if ((crc & 0x0001) != 0) {      // If the LSB is set
        crc >>= 1;                    // Shift right and XOR 0xA001
        crc ^= 0xA001;
      }
      else                            // Else LSB is not set
        crc >>= 1;                    // Just shift right
    }
  }
  // Note, this number has low and high bytes swapped, so use it accordingly (or swap bytes)
  return crc; 
}

Displayed pH value

The number displayed for a pH reading can contain 2 types of data:

Output	Cause	Action
nn.nn	Sensor measuring pH	No action required
99.99	Error	Please check the transducer health number for instruction

Displayed Salinity/Conductivity value

Salinity and conductivity are available for salinities up to 7ppt.
The number displayed for a salinity or conductivity reading can contain 2 types of data:

Output	Cause	Action
nn.nn	Sensor measuring salinity/conductivity	No action required
99.99	If pH output is ok, the salinity is out of range	If expected salinity is > 7ppt no salinity output is given
99.99	If pH output is not ok	Follow transducer health instructions

Transducer Health

Sensor Diagnostics