Sensor Output

$ANB,CRC,TIMESTAMP,PH,TEMP,SALINITY,CONDUCTIVITY,TRANSDUCER HEALTH,SENSOR DIAGNOSTICS,R,MODBUS ADDRESS,FILE NUMBER,LFCR

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 6) 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

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	- Try changing your salinity setting - If expected salinity is > 7ppt no salinity output is given
99.99	If pH output is not ok	Follow transducer health instructions

Transducer Health

Health number	Explanation	Action
0	Healthy Transducer	No action required
1	Transducer will need abrading soon	- Ensure salinity setting is correct - Abrade the transducer based on scanning profile and access frequency; if accessed daily, wait until the health number reaches 2 before abrading, otherwise, abrade now for sensors not accessed for weeks/months
2	Transducer needs abrading now	- Ensure salinity setting is correct - Abrade the transducer
3	Transducer needs replacing	- Ensure salinity setting is correct - Replace the transducer (or transducer not immersed for sensors with serial numbers less than 300200)
4	Transducer is not immersed	Immerse the sensor
5	No valid reference tracker measurement	Please wait for the next measurement
6	No valid pH measurement	Please wait for the next measurement

Sensor Diagnostics

Diagnostic number	Explanation	Action
0	Healthy Sensor	None
1	Clock Battery Error	If there is no external power to the sensor the real time clock will not hold the programmed time - If the sensor is powered, the time set and data streamed, this failure is not an issue - If the sensor is in automonous mode the clock will fail if disconnected from the power when it was programmed and placed on an external battery -Users can record when the sensor was first switched on (where the sensor's time will be set to 0) and calculate the times externally, or, if this is not viable, contact support@anbsensors.com
2	SD Card Error	Either SD Card has been disabled or A failing in the internal data save has occurred and no new data can be saved to the internal memory - If the sensor is connected to an external communications system the sensor will continue to stream data, however no data will be saved in autonomous mode - Please contact support@anbsensors.com
3	System Error	Contact support@anbsensors.com
4	Modbus Start Delay	Wait for start delay to elapse