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Signet 2610 Process Optical Dissolved Oxygen Sensor

3-2610.091 Rev. A 04/12 English

*3-2610.091*

English

MODBUS Manual

Cable length must not exceed 1220 m (4000 ft)

Power Connections

The red wire provides power for all system modes. Analog output

is enabled by default. The 4 to 20 mA current loop output can be

disabled by setting Modbus device register 49507 to 0. Set it back

to 1 to re-enable the 4 to 20 mA loop.

RDO is a registered trademark of In-Situ

Inc., Fort Collins, CO USA

The RDO

Pro sensor may be connected to a controller or

logger for communication via RS485 Modbus.

Trim back and insulate unused wires. The shielded wire should be

wired to a chassis ground or earth ground.

Red

Black

Blue

Green

Brown

White

Modbus

RS485

–

Modbus

RS485

3-2610-31

RDO Pro Dissolved Oxygen

Programmable Logic Controller

Other Modbus Master

–

Power

Supply

12 to 36 VDC

PLC

No connection

Red

Black

Blue

Green

Brown

White

Power Supply, 12 to 24 VDC +

Power Supply, 12 to 24 VDC –

Modbus RS485 +

Modbus RS485 –

4 to 20 mA Current Loop

SDI-12 Output

3-2610-31

RDO Pro Dissolved Oxygen

Summary of content (5 pages)

PAGE 1
English Signet 2610 Process Optical Dissolved Oxygen Sensor *3-2610.091* 3-2610.091 Rev. A 04/12 English MODBUS Manual The RDO® Pro sensor may be connected to a controller or logger for communication via RS485 Modbus. Power Connections The red wire provides power for all system modes. Analog output is enabled by default. The 4 to 20 mA current loop output can be disabled by setting Modbus device register 49507 to 0. Set it back to 1 to re-enable the 4 to 20 mA loop. Trim back and insulate unused wires.
PAGE 2
Modbus Registers Device Specific Measurement Registers Register Size (registers) Mode & Access Level (R/W) Data Type Description Dissolved Oxygen Concentration 40038 2 R1 float Measured value, C0 40040 1 R1 ushort Parameter ID = 20 40041 1 R1/W2 ushort Units ID 117 = mg/L (default) 118 = μg/L 40042 1 R1 ushort Data Quality ID 40043 2 R1/W3 float Off line sentinel value (default = 0.
PAGE 3
Calibration Registers Register Size (registers) Mode & Access Data Level (R/W) Type Description 40118 2 R1/W3 float Live salinity value (PSU) 40120 2 R1/W3 float Default salinity value (PSU, default = 0.0) 40122 2 R1/W3 float Live barometric pressure (mbar) 40124 2 R1/W3 float Default barometric pressure (mbar, default = 1013.
PAGE 4
Entering Calibration Registers IMPORTANT Calibration is not required. The sensor cap is factory calibrated to 2% accuracy. This is valid for the life of the sensor cap, one year from first reading. Calibrate the sensor using the following procedure: 1. Optional: Read the Sensor Data Cache Timeout register 49463 and store the value. 2. Write the Sensor Data Cache Timeout register 49463 to a value less than your intended sample rate and greater than 1000 milliseconds.
PAGE 5
Calibration Calculations Calibrated oxygen reading: O2RC = C0 + C1 × O2RU Where: C1 = (O2100%Sat)/(O2RUS × O2RUZ) C0 = –C1 × O2RUZ Where: O2100%Sat is the theoretical 100% saturation point O2RUS is the uncalibrated reading at 100% saturation O2RUZ is the uncalibrated reading at 0% saturation References: Standard Methods for the Examination of Water and Wastewater, 20th Ed, 2008. 4500-0 C. Azide Modification. American Public Health Association. USA.