YOKOGAWA DO71 User manual

Technical Optical Dissolved Oxygen, model DO71/DO72
Information MODBUS Communication
TI 12J06J01-00EN-P
Yokogawa Process Analyzers Europe B.V. TI 12J06J01-00EN-P, 1st Edition
Euroweg 2, 3825 HD Amersfoort, The Netherlands Copyright © 2022
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MODBUS Communication - Contents 3
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Contents
Introduction....................................................................................................................................4
1. General ....................................................................................................................................5
1.1 MODBUS setup ...............................................................................................................5
1.2 Function code / Exception code ...................................................................................5
1.3 MODBUS communication..............................................................................................6
1.4 Connection......................................................................................................................6
2. MODBUS map.........................................................................................................................8
2.1 Hold Register DO............................................................................................................9
3. Failures and Warnings DO..................................................................................................17
4. Low/High Point Calibration DO...........................................................................................18
5. Revision History...................................................................................................................19

MODBUS Communication - Introduction 4
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Introduction
This document describes MODBUS communicationby the Optical Dissolved Oxygen (DO) sensor,
model DO71 and DO72, for a basic user.
Before communication using the MODBUS protocol, refer to the User’s Manual of the Optical
Dissolved Oxygen sensors, model DO71 and model DO72 (IM 12J06J01-00EN-P) for details of
the parameters and connections.
Latest revision of the User’s Manual can be downloaded from the website:
https://www.yokogawa.com/solutions/products-platforms/process-analyzers/liquid-
analyzers/#Downloads
You can use the QR-code for quick-access.
NOTE
No part of the Technical Information may be transferred or reproduced without prior written
consent from YOKOGAWA.
YOKOGAWA reserves the right to make improvements in the Technical Information and product
at any time, without notice or obligation.

MODBUS Communication –General 5
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1. General
Optical Dissolved Oxygen sensors are slave devices which can be configured or are sending
process data using Bi-directional digital communication (RS485, half-duplex) with full MODBUS
(RTU) support. The power for the Optical Dissolved Oxygen sensors must be supplied by a HOST
or by a separate power supply in the range +7VDC up to +30VDC. Maximum power of the Optical
Dissolved Oxygen sensors is 1W in active mode, and 150mW in stand-by mode.
1.1 MODBUS setup
The following list shows the required setting by HOST to establish communication between the
HOST as master device and the Optical Dissolved Oxygen sensor as slave device. The procedure
for changing list items is explained in the following chapters in this document.
Slave address : 1
Serial Profile : 19200 bps, 8 data bits, No parity, 2 stop bits
NOTE
Slave address and Serial Profile are configurable as explained in this document.
IncaseofusingmultipleOpticalDissolvedOxygensensorsinabussystem,connectedtooneHOST,
the Slave addresses of all the Optical Dissolved Oxygen sensors must be unique. Because initial
settingofaddressis1itisrecommendedtochangetheinitial addressvaluetopreventcommunication
conflicts in case a new purchased Optical Dissolved Oxygen sensor is added to the bus.
Serial profile of the slave device(s) mustbe the same as the HOST.
1.2 Function code / Exception code
MODBUS Function codes used for DO71 and DO72:
Function
Function code (hex)
Read Hold Register
03
Write Single Register
06
Write Multiple Registers
10
Exception codes used for DO71 and DO72:
Name
Exception code
Meaning
Illegal Function
0x01
The Function code received is not an
allowable action for the slave
Illegal Data Address
0x02
The Data Address received is not an
allowable address for the slave

MODBUS Communication –General 6
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1.3 MODBUS communication
If the Optical Dissolved Oxygen sensor is used with a HOST, the following must be considered.
⚫MODBUS response timing
TheOpticalDissolvedOxygensensor’s HR (HOLDRegister)responsetoaHOSTHR Readrequest
is within 100ms. The timing in between a response and a new request must be at least 10ms.
Figure 1.3: Timing diagram
⚫HOLD Register renewal cycle
Process value sent in HOLD Register is configurable, initial value is 1 s.
1.4 Connection
⚫BUS system
Wired connection:
Figure 1.4: DO71 sensor with HOST
< 100 ms > 10 ms
HOST HR: Hold Register
DO sensor
HR Request
HR Response
HR Request

MODBUS Communication –General 7
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Table 1.4.1: DO71 connection definition
Terminal
pin no.
(Fixed cable)
Wire
colour
Description
12
yellow
RS485 Data + (B)
11
green
RS484 Data –(A)
13
white
Power - GND
10
brown
Power - VDC
14
transparent
Cable shield / Probe body
Table 1.4.2: DO72 connection definition
Terminal
pin no.
(WU10-V-D-xx)
Wire
colour
Connector pin
(Variopin)
Description
12
green
H
RS485 Data + (B)
11
yellow
G
RS484 Data –(A)
13
white-shield
D
Power - GND
10
white-core
C
Power - VDC
14
black
Shield
Cable shield /
Probe body
xx: Cable length in meters

MODBUS Communication –MODBUS map 8
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2. MODBUS map
Data type for Optical Dissolved Oxygen sensor MODBUS map:
Data type
Definition
Float
floating point (4byte, little endian byte swap [CDAB])
IEEE754
NaN: 0x7FFFFFFF
Uint32
32 bit unsigned integer, little endian byte swap [CDAB]
ASCII
character set (using one byte per character), multiple registration possible,
little endian byte swap [CDAB])
Access (load/import) to multiple data types, such as Float, Uint32, ASCII etc., must be
implemented at once. The current version does not support Script yet.
Access
Function
Function Code (hex)
Data Access
16 bits
Read Hold Registers
03
Write Single Register
06
Write Multiple Register
10
Hold Registers are Read only (R) or Read/Write (R/W).
NOTE
The content of this Modbus Map is based upon DO71 firmware YPA 1.4.0.xx and DO72 firmware
YPA 1.4.0.xx

MODBUS Communication –Hold Register DO 9
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2.1 Hold Register DO
If applicable, in the Value/description field the Factory Default setting (D), Low limit setting (L) and
High limit setting (H) are explained. NaN does mean that there is Not a Number defined.
NOTE
Because no limit checks are implemented, incorrect settings or settings outside the specified range
are accepted as is. Pleasetake care that settings aredone correctly and within the specified range.
Address
Item name
Data type
Access
Value / description
1031
Firmware version
ASCII
R
Alphanumeric Firmware version code:
16 bytes, 8 addresses
2089
Oxygen unit
Uint32
R/W
0x 0000 0010 % vol O2
0x 0000 0020 % air saturation
0x 0000 0040 ppb (µg/L) 2)
0x 0000 0080 ppm (mg/L) 2)
0x 0400 0000 µmol/L 2)
0x 0800 0000 % DO saturation
0x 2000 0000 hPa (mbar)
0x 4000 0000 ppm gas 1) 2)
0x 8000 0000 Torr
Remark:
1) ppm gas only possible with DO72-T
2) Setting not possible in
measurement mode “Dry”
(register HR5703)
D: % DO saturation
2091
Oxygen value
Float
R
Calculated oxygen value in oxygen unit
as defined in register HR2089
Remark:
1) The calculated oxygen value is only
updated if an interval rate is set
(register HR3499)
2) When value is -999 this means
there is no calculated output
2093
Error
Uint32
R
For details see Section 3.1
2409
Temperature Unit
Uint32
R/W
0x 0000 0002 K
0x 0000 0004 °C
0x 0000 0008 °F
D: °C
2411
Temperature Value
Float
R
Measured temperature value used for
temperature compensation

MODBUS Communication –Hold Register DO 10
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Address
Item name
Data type
Access
Value / description
3115
Salinity
Float
R/W
Salinity value used for salinity
compensation (unit is g/L)
D: 0
3145
Pressure Comp. Unit
Uint32
R
0x 0080 0000 hPa (mbar)
Remark:
1) This is a fixed unit
D: hPa (mbar)
3147
Volatile Pressure Comp. Value
Float
R/W
Pressure value in hPa (mbar) used for
oxygen calculation
Remark:
1) If included in a multi register write,
no change will take place
2) Value is not written into Flash
memory
D: By default, this is the Persistent
Pressure Comp. value (register
HR3153)
3153
Persistent Pressure Comp. Value
Float
R/W
Default setting for compensation
pressure value in hPa (mbar)
Remark:
1) Do not use this register frequently
due to limited number of write
cycles into Flash memory. For
frequent pressure changes please
use register HR3147
2) Value is stored into Flash memory
and restored at startup
D: Set by manual input
3497
Interval Unit
Uint32
R/W
0x 0000 0001 seconds
Remark:
1) This is the time unit for the oxygen
measurement interval rate, fixed
set to seconds
D: seconds
3499
Interval rate
Uint32
R/W
Oxygen measurement interval rate in
time unit as set in register HR3497
Remark:
1) Setting the interval rate to 0
deactivates the continuous
measurement
(see register HR9000)
D: 1
L: 0
H: 300

MODBUS Communication –Hold Register DO 11
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Address
Item name
Data type
Access
Value / description
4095
Device ID
Uint32
R/W
Modbus address
Remark:
1) Setting is effective immediately
D: 1
L: 1
H: 247
4097
Reserved
Uint32
R
4099
Reserved
Uint32
R
4101
Baud rate
Uint32
R/W
0x 0000 0002 4800 baud
0x 0000 0003 9600 baud
0x 0000 0004 19200 baud
0x 0000 0005 38400 baud
0x 0000 0006 57600 baud
0x 0000 0007 115200 baud
Remark:
1) Setting is effective immediately
D: 19200
L: 4800
H: 115200
4103
Reserved
Uint32
R
4105
Reserved
Uint32
R
4107
Parity
Uint32
R/W
0x 0000 0000 Even parity /1 Stop bit
0x 0000 0001 Odd parity / 1 Stop bit
0x 0000 0002 No parity / 2 Stop bits
Remark:
1) Setting is effective immediately
D: No parity
2 Stop bits
4607
Operating Temp. min
Float
R
The minimum operating temperature of
the sensor
D: -50°C
4609
Operating Temp. max
Float
R
The maximum operating temperature of
the sensor
D: +130°C
4611
Measurement Temp. min
Float
R/W
The minimum measurement tempera-
ture of the sensor
Remark:
1) Sensor precision is only specified
within the range 0…+50°C
D: -40°C

MODBUS Communication –Hold Register DO 12
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Address
Item name
Data type
Access
Value / description
4613
Measurement Temp. max
Float
R/W
The maximum measurement tempera-
ture of the sensor
Remark:
1) Sensor precision is only specified
within the range 0…+50°C
D: +100°C
4615
Calibration Temp. min
Float
R
The minimum value of the temperature
calibration range
D: 0°C
4617
Calibration Temp. max
Float
R
The maximum value of the temperature
calibration range
D: +50°C
4677
Hours out of Measurement Temperature
Range
Float
R
Accumulated hours in which the sensor
was out of the defined measurement
temperature range (see registers
HR4611 and HR4613)
D: 0
4679
Hours out of Operating Temperature
Range
Float
R
Accumulated hours in which the sensor
was out of the defined operating
temperature range (see registers
HR4607 and HR4609).
D: 0
4895
Pressure Value Raw
Float
R
Measured pressure value in hPa (mbar)
4897
Reference Amplitude Value Raw
Float
R
Reference amplitude raw value in µV
4899
Oxygen Amplitude Value Raw
Float
R
Measured oxygen amplitude raw value
in µV
4901
Oxygen Phase Value Raw
Float
R
Measured oxygen phase shift in degrees
4903
Temperature Value Raw
Float
R
Measured temperature value in the unit
defined in HR2409
4905
Calculated Oxygen Value
Float
R
Calculated Oxygen Value in the unit
defined in register HR2089
4907
Measurement Error
Uint32
R
For details see Section 3.1

MODBUS Communication –Hold Register DO 13
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Address
Item name
Data type
Access
Value / description
4911
Sensor Constant f1
Float
R/W
Sensor constant f1
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: 0.001
H: 0.999
4913
Sensor Constant dPhi1
Float
R/W
Sensor constant dPhi1
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: -0.19999
H: 0.19999
4915
Reserved
Uint32
R
D: NaN
4917
Sensor Constant dPhi2
Float
R/W
Sensor constant dPhi2
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: -0.19999
H: 0.19999
4919
Sensor Constant dKSV1
Float
R/W
Sensor constant dKSV1
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: -0.199999
H: 0.199999
4921
Sensor Constant dKSV2
Float
R/W
Sensor constant dKSV2
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: -0.199999
H: 0.199999
4923
Sensor Constant m
Float
R/W
Sensor constant m
Remark:
1) The default value is printed on the
Quality Inspection Certificate
(Q.I.C.)
L: 0.01
H: 999.99

MODBUS Communication –Hold Register DO 14
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Address
Item name
Data type
Access
Value / description
5157
Oxygen Calibration Low Point Status
Uint32
R
For details see Section 4
5159
Oxygen Unit for Oxygen Calibration Low
Point
Uint32
R
0x 0800 0000 % DO saturation
Remark:
1) Shows the oxygen unit for the
oxygen calibration low point.
D: % DO saturation
5161
Activate Oxygen Calibration Low Point
Float
R/W
Write any value to trigger a calibration
for the low oxygen calibration point.
If no calibration error regarding the low
point (bits 2 to 7, see Table 4.1)
occurred, the measured phase and
temperature values (or the manually set
temperature value) will be written in the
registers for Cal0 (register HR5521) and
T0 (register HR5523)
5181
Low Calibration Point Timestamp
Uint32
R
The timestamp the last low point
calibration point was performed
5189
Oxygen Calibration High Point Status
Uint32
R
For details see Section 4
5193
Activate Oxygen Calibration High Point
Float
R/W
Write the desired O2-2nd value to trigger
a calibration for the high oxygen
calibration point. The unit is set in
HR5535.
If no calibration error regarding the high
point (bits 10 to 15, see Table 4.1)
occurred, the measured phase,
pressure, and temperature values (or
the manually set temperature value) will
be written in the registers for Cal-2nd
(register HR5529), T2nd (register
HR5531) and pATM (register HR5533)
5213
High Calibration Point Timestamp
Uint32
R
The timestamp the last high point
calibration point was performed

MODBUS Communication –Hold Register DO 15
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Address
Item name
Data type
Access
Value / description
5517
Calibration Mode
Uint32
R/W
Measurement mode during calibration:
0: Humid
1: Dry
D: 0 (for wide range sensors)
D: 1 (for trace range sensors)
5521
Cal0
Float
R/W
Calibration value of Phase shift at the
low oxygen calibration point
L: 30.01
H: 79.99
5523
T0
Float
R/W
Calibration value of Temperature at the
low oxygen calibration point
L: 10.01
H: 29.99
5525
Reserved
Uint32
R
5527
O2-2nd
Float
R/W
Calibration value of Oxygen
concentration (unit defined in HR5535)
at the high oxygen calibration point
L: 0.001
H: 299.999
5529
Cal-2nd
Float
R/W
Calibration value of Phase shift at the
high oxygen calibration point
L: 10.01
H: 49.99
5531
T2nd
Float
R/W
Calibration value of Temperature at the
high oxygen calibration point
L: 10.01
H: 29.99
5533
pATM
Float
R/W
Calibration value of Pressure (in hPa) at
the high oxygen calibration point
L: 901
H: 1099
5535
O2-2nd Unit
Uint32
R/W
0x 0800 0000 % DO saturation
Remark:
1) The unit for the O2-2nd value, for set
values see HR2089
D: % DO saturation
5703
Measurement Mode
Uint32
R/W
Measurement mode:
0: Humid
1: Dry
D: 0
6437
Calibration counter
Uint32
R/W
Counts the number of Low/High Point
Calibrations
D: 0
6457
Serial Number YPA
ASCII
R
Alphanumeric Serial Number code:
16 bytes, 8 addresses

MODBUS Communication –Hold Register DO 16
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Address
Item name
Data type
Access
Value / description
8231
Timestamp
Uint32
R/W
The timestamp set by the user
application.
Remark:
1) During reboot this timestamp is
reset to 0 and must be set (again)
to a value representing local time
2) Register is automatically
incremented every second
3) Timestamp will be saved to the
applicable calibration timestamp
(register HR5181 or HR5213) on
the event of a calibration process
9000
Measurement Status
Uint32
R
Triggers a single scan using the
following code table:
Bit 0 Continuous measurement
Off (0) / On (1)
Setting is a result of the interval
rate setting in register HR3499

MODBUS Communication –Failures and warnings DO 17
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3. Failures and Warnings DO
Device failures and Measurement warnings are checked and identified by bit content (0 or 1) in
specific Hold Registers (HR2093 and HR2094). The definition of each bit, the root cause and
possible remedy are explained in table 3.1.
Table 3.1: Bit assignment for DO71/DO72 failures/warnings
Bit#
Bit definition
Root cause & Remedy
0: 0x00000000
Reference channel overflow
Reference amplitude too high.
Decrease reference current.
1: 0x00000002
Temperature too high
The temperature is too high for
performing a measurement.
2: 0x00000004
Reference photo detector overflow A
Reference amplitude is too
low/high;
Sensor cap is not attached;
Too much ambient light.
Adjust reference current;
Attach sensor cap;
Reduce ambient light.
3: 0x00000008
Signal channel overflow
Signal amplitude too high.
Decrease signal current.
4: 0x00000010
Reserved
5: 0x00000020
Reserved
6: 0x00000040
No sensor calculation /
Amplitude too low
Signal amplitude is too low;
Sensor cap is not attached.
Decrease signal current;
Attach sensor cap.
7: 0x00000080
Pulse counter overflow
Pulse counter reached its
maximum value.
8: 0x00000100
Reference amplitude out of range
Reference amplitude is too
low/high;
Sensor cap is not attached.
Adjust reference current;
Attach sensor cap.
9: 0x00000200
Signal photo detector overflow
Signal amplitude is too high;
Sensor cap is not attached;
Too much ambient light.
Adjust signal current;
Attach sensor cap;
Reduce ambient light.
10: 0x00000400
Reference photo detector overflow B
Reference amplitude is too
low/high;
Sensor cap is not attached;
Too much ambient light.
Adjust reference current;
Attach sensor cap;
Reduce ambient light.
11: 0x00000800
Memory Write error detected
Memory errors occurred.
Contact the relevant
YOKOGAWA sales office.
12: 0x00001000
PME timeout
Internal error.
Contact the relevant
YOKOGAWA sales office.

MODBUS Communication –Calibration DO 18
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4. Low/High Point Calibration DO
Low/High Point Calibration status register explains if calibration process is executed successfully.
If any error regarding the low/high point was present this is identified by bit content change (0 to
1) in specific Hold Registers (low point: HR5157 and high point: HR5189). The definition of each
bit is explained in table 4.1.
Table 4.1: Bit assignment for DO71/DO72 calibration failures
Bit#
Bit definition
0: 0x00000000
Reserved
1: 0x00000002
Reserved
2: 0x00000004
Temperature value too low while calibrating the low point
3: 0x00000008
Temperature value too high while calibrating the low point
4: 0x00000010
Temperature value not stable while calibrating the low point
5: 0x00000020
Reserved
6: 0x00000040
Reserved
7: 0x00000080
Phase value not stable while calibrating the low point
8: 0x00000100
Reserved
9: 0x00000200
Reserved
10: 0x00000400
Temperature value too low while calibrating the high point
11: 0x00000800
Temperature value too high while calibrating the high point
12: 0x00001000
Temperature value not stable while calibrating the high point
13: 0x00002000
Reserved
14: 0x00004000
Reserved
15: 0x00008000
Phase value not stable while calibrating the high point

MODBUS Communication –Revision History 19
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5. Revision History
October 2022 1st Edition