In-Situ Aqua TROLL 400 Modbus and SDI-12 Reference Guide - Manual (Page 49)

8. Optionally, read the Last User Calibration Time, add the next calibration interval,
and write the result to the Next User Calibration Time register.
9. Write the Calibration Off command (0xE002) to the Sensor Command register to
place the sensor in normal operation.
7. Modbus Registers – pH/ORP Sensor
The Sensor Map Data Register Offset points to the first register in the sensor data header block.
The current value for this sensor data register map version is 1.
The pH/ORP sensor registers remain valid even if the sensor is not installed.
7.1 Header Registers
The sensor map data register offset points to the first register in the sensor data header block.
Register Size
(registers)
Mode & Access Level
(R/W)
Data
Type
Description
1501 1 R1/W4 ushort Sensor ID
0 = not installed
27 = pH/ORP
1502 2 R1/W4 ulong Sensor serial number (0 – 65535)
1504 1 R1 16 bits Sensor status
1505 3 R1/W4 time Last factory calibration
1508 3 R1 time Next factory calibration
(0 = none required)
1511 3 R1 time Last user calibration
1514 3 R1/W2 time Next user calibration
(0 = none required)
1517 1 R1 ushort Warm-up time =
1300 milliseconds
1518 1 R1 ushort Fast sample rate =
1300 milliseconds
1519 1 R1 ushort Number of sensor parameters
(N = 3)
1520 1 R1/W3 ushort Alarm/warning parameter number
(1 – N, default = 1)
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