User Guide For Optical Dissolved Oxygen Sensor with Modbus output MBRTU-PODO USER GUIDE FOR OPTICAL DISSOLVED OXYGEN SENSOR MODBUS OUTPUT MBRTU-PODO JUN-2021 This document is applied for the following products 1. Introduction Optical Dissolved Oxygen Sensor with Modbus output MBRTU-PODO Accurate and low maintenance optical dissolved oxygen technology (luminescent quenching ). RS485/Modbus signal output. Industry standard, robust body housing with 3⁄4” NPT on front and back. Flexible cable outlet: fixed cable (0001) and detachable cable (0002). Integrated (probe-mounted) waterproof pressure sensor. Automatic temperature and pressure compensation. Automatic salinity compensation with user-input conductivity/salinity concentration value. Convenient sensor cap replacement with integrated calibration. 2. Specification Range DO Saturation %: 0 to 500%.DO Concentration : 0 to 50 mg/L (ppm). Operating Temperature: 0 to 50°C.Storage Temperature: -20 to 70°C.Operating Atmospheric Pressure: 40 to 115 kPa. Maximum Bearing Pressure: 1000 kPa. Response Time DO: T90 ~ 40s for 100 to 10%.Temperature: T90 ~ 45s for 5 - 45oC (w/ stirring). Accuracy DO: 0-100% < ± 1 %. 100-200% < ± 2 %. Temperature: ± 0.2 °C. Pressure: ± 0.2 kPa. Input /output/protocol Input: 4.5 - 36 V DC.Consumption: average 60 mA at 5V. Output: RS485/Modbus or UART. Calibration 1-point (100% cal point) in air-saturated water or water-saturated air (calibration bottle).2-point: (Zero and 100% cal points). DO Compensation Factors Temperature: automatic, full range.Salinity: automatic with user-input (0 to 55 ppt). Pressure: 1) compensation by instantaneous pressure value if pressure sensor is above water or less than 20cm of water. 2) Compensation by default pressure value if the pressure sensor is more than 20cm of water. The default is obtained by the pressure sensor in the last 1-point calibration and recorded in probe memory. Resolution Low range (<1 mg/L): ~ 1 ppb (0.001 mg/L). Mid range (<10 mg/L): ~ 4-8 ppb (0.004-0.008 mg/L). High range (>10 mg/L): ~10 ppb (0.01 mg/L).* *The higher range, the lower resolution. Expected Sensor Cap Life A useful life of up to 2 years is feasible in optimum situations. Others Waterproof: IP68 rating with fixed cable. Certifications: RoHs, CE, C-Tick (in process). Materials: Ryton (PPS) body.Cable length: 6 m (options exist). 3. Product Pictures 4. Wiring Please wiring as shown below: Wire color Description Red Power (4.5 ~ 36 V DC) Black GND Green UART_RX (for upgrading or PC connection ) White UART_TX (for upgrading or PC connection) Yellow RS485A Blue RS485B Note: The two UART wires could be cut if not upgrading/programming probe. 5. Calibration and Measurement DO Calibration in Options 5.1. Reset calibration a) Reset 100% calibration. The user write 0x0220 = 8 b) Reset 0% calibration. The user write 0x0220 = 16 c) Reset temperature calibration. The user write 0x0220 = 32 5.2. 1-point calibration 1-point calibration means calibrating the probe in the point of100 % saturation, which can be obtained by one of the following means: a) In air-saturated water (standard method). The air-saturated water (for example of 500 mL) can be obtained by continuously (1) purging water with air using an air bubbler or some type of aeration about 3 ~ 5 minutes, or (2) stirring water by magnetic stirrer under 800 rpm for 1 hour. After air-saturated water is ready, immerse the sensor cap and temperature sensor of the probe in the air-saturated water, and calibrate probe after the reading becomes stable (usually 1 ~ 3 minutes). The user write 0x0220 = 1 , then waiting 30 seconds. If the final reading of 0x0102 is not in 100 ± 0.5%, please check if the stability of current testing environment or try again. b) In water-saturated air (convenient method). Alternatively, the 1-pt calibration can be easily done using water-saturated air, but 0 ~ 2% error might be caused depending on different operations. The recommended procedures are given as below: i)  immerse the sensor cap and temperature sensor of the probe in fresh/tap water 1~2 minutes. ii)  get out the probe and quickly dip dry the water on the surface of sensor cap by tissue. iii) install the sensor end in the calibration/storage bottle with a wet sponge inside. Avoid direct contact of the sensor cap with any water in the calibration/storage bottle during this calibration step. Keep the distance between the sensor cap and the wet sponge being ~ 2 cm.v) wait for the readings to stabilize (2 ~ 4 minutes ) and then write 0x0220 = 2. 5.2. 2-point calibration (100% and 0% saturation points) (i)  Put the probe in air-saturated water, write 0x0220 = 1 after the DO reading stabilizes. (ii)  After DO reading becomes 100%, move the probe to zero oxygen water (use sodium sulfide added in excess to a water sample). (iii)  Write 0x0220 = 2, after the DO reading stabilizes (~at least 2 mins). (iv) The user reading saturation at 0x0102 for 1-point calibration, 0x0104 for 2-point calibration. 2-point cal is not necessary for most applications, unless users need a very accurate measurement in low DO concentration (<0.5 ppm). Enforcement of “0% calibration” without “100% calibration” is not allowed. 5.3. Point calibration for temperature i) The user write 0x000A = the ambient temperature x100 (Ex: If the ambient temperature = 32.15, then the user write 0x000A=3215).ii) The user reading temperature at 0x000A . If it is equal to what you inputted, the calibration is done. If not, please try Step 1 again. 6. Modbus RTU Protocol: 6.1. Command structure: Commands should not be sent sooner than 50mS from the completion of the last response. If the expected response from the slave is not seen for > 25mS, throw a communication error. Probe follows Modbus standard for functions 0x03, 0x06, 0x10, 0x17 6.2. Serial Transmission structure: Data types are big-endian unless otherwise noted. Each RS485 transmission will have: one start bit, 8 data bits, no parity bit, and two stop bits; Default Baud rate: 9600 (some of the probes may have the Baudrate of 19200); Default Slave address: 1 The 8 data bits transmitted after the start bit are the most significant bit first. Bit Sequence Start bit 1 2 3 4 5 6 7 8 Stop bit 6.3. Timing: Firmware updates must be run within 5 seconds of power on or soft reset Probe tip LED will be solid blue during this time First command cannot be run earlier than 8 seconds from power on or soft reset If there is no expected response from an issued command timeout occurs after 200ms 6.4. Modbus RTU protocol: Register # R/W Details Type Notes 0x0003 R LDO (mg/L) x100 Uint16 0x0006 R Saturation % x100 Uint16 0x0008 R/W Salinity (ppt) x100 Uint16 0x0009 R Pressure (kPa) x100 Uint16 0x000A R Temperature (°C) x100 Uint16 0x000F R Baud Rate Uint16 Note 1 0x0010 R Slave Address Uint16 0x0011 R Probe ID Uint32 0x0013 R Sensor Cap ID Uint32 0x0015 R Probe Firmware Version x100 Uint16 Note 2 0x0016 R Probe Firmware Minor Revision Uint16 Note 2 0x0063 W Baud Rate Uint16 Note 1 0x0064 W Slave Address Uint16 0x0100 R LDO (mg/L) Float 0x0102 R Saturation % Float 0x0108 R Pressure (kPa) Float 0x010A R Temperature (°C) Float 0x010C R/W Current Probe Datetime 6 bytes Note 3 0x010F R Error bits Uint16 Note 4 0x0117 R Salinity (ppt) Float 0x0132 R/W Temperature Offset Float 0x0220 R/W Calibration Bits Uint16 Note 5 0x02CF R Membrane Cap Serial Number Uint16 0x0300 W Soft restart Uint16 Note 6 Note: Note 1: Baud rate values: 0= 300, 1= 2400, 2= 2400, 3= 4800, 4= 9600, 5= 19200, 6=38400, 7= 115200. Note 2: Firmware version is address 0x0015 divided by 100, then a decimal then address 0x0016. Example: if 0x0015 = 908 and 0x0016 = 29, then the firmware version is v9.08.29. Note 3: Probe has no RTC, if probe is not supplied continuous power or is reset all values will reset to 0. Datetime bytes are year, month, day, day, hour, minute, second. Most significant to least. Example: iftheuserwrites0x010C=0x010203040506,thentheDatetime will be set to February 3rd, 2001 4:05:06 am. Note 4: Bits are counted least significant to most, starting at 1: o Bit 1 = Measurement Calibration Error.o Bit 3 = Probe Temperature out of range, maximum 120 °C.o Bit 4 = Concentration out of range: minimum 0 mg/L, maximum 50 mg/L. o Bit 5 = Probe Pressure Sensor Error.o Bit 6 = Pressure Sensor out of range: minimum 10 kPa, maximum 500 kPa. Probe will use default pressure = 101.3 kPa.o Bit 7 = Pressure Sensor Communication error, Probe will use default pressure = 101.3 kPa. Note 5: Write (0x0220) 1 Run 100% calibration. 2 Run 0% calibration. 8 Reset 100% calibration. 16 Reset 0% calibration. 32 Reset temperature calibration. Note 6: If 1 is written to this address a soft restart is performed, all other read/writes are ignored. Note 7: if the probe has a built in pressure sensor this is a read only address. Note 8: These Values are results of 2 point calibration, while the address of 0x0003 and 0x0006 present the results of 1 point calibration. 6.5. Example Transmissions CMD: Read Probe Data Raw Hex: 01 03 0003 0018 B5C0 Address Command Start Address # of Registers CRC 0x01 0x03 0x0003 0x0018 0xB5C0 1 Read 3 0x18 Example 1 response from probe: Raw Hex: 01 03 30 031B 0206 0000 2726 0208 0BB8 27AA 0AAA 0000 0000 0000 0BB8 0005 0001 0001 0410 0457 0000 038C 0052 0001 031D 2741 0000 FAD4 Concentration (mg/L) Saturation % Salinity (ppt) Pressure (kPa) Temperature (°C) Concentration 2pt (mg/L) Saturation % 2pt 0x031B 0x2726 0x0BB8 0x27AA 0x0AAA 0x031D 0x2741 7.95 mg/L 100.22% 30 ppt 101.54 kPa 27.30 °C 7.97 mg/L 100.49% Example 2 response from probe: Raw Hex: 01 03 30 0313 0206 0000 26F3 0208 0000 27AC 0AC8 0000 0000 0000 0000 0005 0001 0001 0410 0457 0000 038C 0052 0001 031A 2748 0000 5BC0 Concentration (mg/L) Saturation % Salinity (ppt) Pressure (kPa) Temperature (°C) Concentration 2pt (mg/L) Saturation % 2pt 0x0313 0x26F3 0x0000 0x27AC 0x0AC8 0x031A 0x2748 7.87 mg/L 99.71% 0 ppt 101.56 kPa 27.60 °C 7.94 mg/L 100.56 % CMD: Run 100 % Calibration Raw Hex: 01 10 0220 0001 02 0001 4330 Address Command Start Address # of Registers # of Bytes Value CRC 0x01 0x10 0x0220 0x0001 0x02 0x0001 0x4330 1 Write Multi 544 1 2 Run 100% Cal Example 1 response from probe: Raw Hex: 01 10 0220 0001 01BB Success! CMD: Run 0 % Calibration Raw Hex: 01 10 0220 0001 02 0002 0331 Address Command Start Address # of Registers # of Bytes Value CRC 0x01 0x10 0x0220 0x0001 0x02 0x0002 0x0331 1 Write Multi 544 1 2 Run 0% Cal Example 1 response from probe: Raw Hex: 01 10 0220 0001 01BB Success! CMD: Update Salinity = 45.00 ppt, Pressure =101.00 kPa, and Temperature = 27.00 °C Raw Hex: 01 10 0008 0003 06 1194 2774 0A8C 185D Address Command Start Address # of Registers # of Bytes Value CRC 0x01 0x10 0x0008 0x0003 0x06 0x1194 2774 0A8C 0x185D 1 Write Multi 719 1 2 45, 101, 27 Example 1 response from probe: Raw Hex: 01 10 0008 0003 01CA Success! CMD: Update Cap Number with 1111 Raw Hex: 01 10 02CF 0001 02 0457 D751 Address Command Start Address # of Registers # of Bytes Value CRC 0x01 0x10 0x02CF 0x0001 0x02 0x0457 0xD751 1 Write Multi 719 1 2 1111 Example 1 response from probe: Raw Hex: 01 10 02CF 0001 304E Success! 7. Dimensions 8. Maintenance 8.1. Probe maintenance includes cleaning the sensor cap, as well as the proper conditioning, preparation, and storage of the test system. 8.2. When the probe is not in use, it is highly recommended to store the probe with its sensor cap installed and the calibration/storage bottle which was included in the original packaging, threaded onto the probe. A beaker of clean water or a moist/humid capping mechanism can also suffice if the calibration/storage bottle is not available. The sponge inside the calibration/storage bottle should be kept moist for best results. 8.3. Avoid sensor cap touching organic solvent, scratching, and abusive collisions to strengthen and lengthen the working life of the sensor cap. Special care should be taken to clean the coating of cap, to dip probe and cap in fresh water, and then to tap dry the surface with a tissue. Do not wipe the coating surface. 8.4. Replace the sensor cap, if the cap coating is faded or stripped away. DO NOT touch the clear window on the probe tip after unscrewing the old cap. If any contaminants or residue are present on the window or inside the cap, carefully remove them with a powder free wipe. Then re-screw the new sensor cap onto the probe. 9. Contact Manufacturer Daviteq Technologies Inc No.11 Street 2G, Nam Hung Vuong Res., An Lac Ward, Binh Tan Dist., Ho Chi Minh City, Vietnam.Tel: +84-28-6268.2523/4 (ext.122) Email: info@daviteq.com | www.daviteq.com