Xylem DIQ/S 281 User manual

OPERATING MANUAL
ba76226e02 03/2023
DIQ/S 281
UNIVERSAL TRANSMITTER FOR ONE DIGITAL SENSOR
UNIVERSALTRANSMITTER
DIQ/S 281

2ba76226e02 03/2023
IQ SENSORNET System 281
Contact YSI
1725 Brannum Lane
Yellow Springs, OH 45387 USA
Tel: [phone]
800-765-4974
Email: [email protected]
Internet: www.ysi.com
Copyright © 2022 Xylem Inc.
For the most recent version of the manual, please visit
www.ysi.com.

DIQ/S 281 Contents
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Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1 Structure and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.1 USB interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.2 Fieldbus interface (DIQ/S 281-MOD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3 Behavior of the system to a power failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1 Safety information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1 Safety information in the operating manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2 Safety signs on the product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.3 Further documents providing safety information . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Safe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2.1 Authorized use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2.2 Requirements for safe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2.3 Unauthorized use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 User qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Scopes of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Basic principles of installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 Requirements of the measurement location . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Safety requirements of the electrical installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4 Installation guidelines for lightning protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.5 Connecting system components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.5.1 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.5.2 Stacked mounting of DIQ and MIQ modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.5.3 Distributed mounting of MIQ modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.5.4 Connecting the sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.5.5 IQ sensor with SNCIQ cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.5.6 IQ sensor with permanently mounted cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.6 On-site mounting of the DIQ/S 281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.6.1 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.6.2 Mounting on a mounting stand with the SSH/IQ sun shield . . . . . . . . . . . . . . . . . 34
3.6.3 Mounting under the SD/K 170 sun shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.6.4 Top hat rail mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.6.5 Panel mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.7 Electrical connections: General instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.8 Connecting the voltage supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.8.1 DIQ/S 281 (line power version) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8.2 DIQ/S 281/24V (24 V version) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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3.9 Connections to the relay and current outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.9.1 General installation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.9.2 Usage of the auxiliary voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.10 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.11 Installation examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.11.1 Connection of a sensor without compressed air cleaning . . . . . . . . . . . . . . . . . . . 54
3.11.2 Connection of a sensor with compressed air cleaning . . . . . . . . . . . . . . . . . . . . . 55
3.11.3 Connection of a sensor that is located at a distance
(without compressed air cleaning) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.12 Figures of the terminal strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.1 Operating elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.1.1 Overview of the operating elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.1.2 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.1.3 Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.2 General operating principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.2.1 Navigating in menus, lists and tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.2.2 Entering texts or numerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.3 Access to the DIQ/S 281 with active access control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.4 Display of current measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.5 Messages and log book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.5.1 Message types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.5.2 Log book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.5.3 Viewing detailed message texts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.5.4 Acknowledge all messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.6 Calibration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.6.1 Calibration entries in the log book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.6.2 Calibration history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.7 Status info of sensors and outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.8 General course when calibrating, cleaning, servicing or repairing an IQ sensor . . . . 74
4.8.1 Maintenance condition of IQ sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.8.2 Switching on the maintenance condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.8.3 Switching off the maintenance condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.9 USB interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.10 Info on software versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.11 Software-Update for the DIQ/S 281 and sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5 Settings/setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
5.1 Selecting the language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.2 Terminal settings of the DIQ/S 281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.3 Access control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.3.1 Activating the access control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3.2 Activating the instrument block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.3.3 Electronic key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.3.4 Access to the DIQ/S 281 with active access control . . . . . . . . . . . . . . . . . . . . . . . 86
5.4 Settings for sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

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5.5 Editing the list of outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.6 Alarm settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.6.1 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.6.2 Setting up / editing alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.6.3 Alarm output to display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5.6.4 Alarm output as relay action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.7 System settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.7.1 Setting the date and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.7.2 Location altitude / average air pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
5.7.3
Function code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.1 Outputs of the DIQ/S 281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.2 Basic information on relay functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.2.1 Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.2.2 Limit indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.2.3 Proportional output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.3 Entering / editing the name of an output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.4 Linking the output with a sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.5 Deleting a link with an output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.6 Setting the relay outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.6.1 Relay action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6.6.2
System monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.6.3
Sensor monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6.6.4
Limit indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6.6.5
Frequency controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6.6.6
Pulse-width output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.6.7
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.6.8
Manual control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.6.9
Alarm contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.7 Setting the current outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
6.7.1
Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
6.7.2
PID controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.7.3
Fixed current value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.8 Checking the condition of the outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.9 Behavior of linked outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.9.1 Behavior in case of error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.9.2 Behavior in non-operative condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7 Maintenance and cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8 What to do if ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128
8.1 Information on errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.2 Errors: causes and elimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.3 Replacing system components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

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8.3.1 Replacing passive components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.3.2 Replacing the IQ sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
9.1 DIQ/S 281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
9.2 DIQ/JB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
9.3 DIQ/CHV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
9.4 Space required by mounted components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
9.4.1 DIQ/S 281 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
9.4.2 DIQ/S 281 with an additional component (stack mounting) . . . . . . . . . . . . . . . . 139
10 Accessories and options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
11 Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
11.1 Explanation of the message codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
11.1.1 Error messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
11.1.2 Informative messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
12 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
13 Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
13.1 Ordering & Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
13.2 Service Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

DIQ/S 281 Overview
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1 Overview
1.1 Structure and function
One digital single sensor (one sensor for one main parameter) can be con-
nected to the universal transmitter DIQ/S 281.
This means one main parameter (e.g. pH, D.O., turbidity value...) and one
secondary parameter in addition (e.g. temperature) can be displayed and
administrated.
Each sensor is automatically recognized after being connected and immediately
starts measuring.
For connection to existing process control systems, the universal transmitter
DIQ/S 281 has the following outputs:
Suitable sensors for the universal transmitter DIQ/S 281 are listed
in the YSI catalog or on the Internet.
DIQ/S 281 variant Outputs
DIQ/S 281 -CR2 2 relay outputs
2 current outputs
DIQ/S 281-MOD 2 relay outputs

Overview DIQ/S 281
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8
Components to
extend the system
Branches The DIQ/JB branching module (accessory) is a simple passive module for the
branching or extending of SNCIQ lines.
Relay and current
outputs
The relay- and current outputs can be linked with the sensor. Linked outputs can
be used to monitor sensors and for the output of measured values.
A relay output can be programmed as:
Monitoring relay
Limit monitor
Proportional output of measured values (pulse width or frequency output)
Control unit of a sensor cleaning system driven by compressed air.
A current output can be programmed as:
Analog output
PID controller
Modbus Only for the variant DIQ/S 281-MOD
For details, see operating manual "Field bus linking"
Compressed air-
driven cleaning
system
The universal transmitter DIQ/S 281 is prepared for the compressed air-driven,
time-controlled sensor cleaning function. For this, a DIQ/CHV valve module and
if necessary a CH cleaning head is required (both available as accessories). The
cleaning procedure is controlled by the Universal Transmitter. The universal
transmitter provides the supply voltage and control relay for the compressed air
Function Component
Passive
compo-
nents
Power supply module MIQ/PS
Radio link (with power supply unit) MIQ/WL PS
Branching
(interfaces for sensors)
DIQ/JB, MIQ/JB
Active
compo-
nents
Relays DIQ/CR3, MIQ/CR3
Current outputs DIQ/CR3, MIQ/CR3,
MIQ/C6
More
compo-
nents
Valve output DIQ/CHV
Maximum extensibility of the system:
Passive components: no limitation
Valve outputs: maximum 1 output per sensor
Active components: 1

DIQ/S 281 Overview
9
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valve in the DIQ/CHV valve module. This enables a simple setup and uncompli-
cated wiring.
Example of a
simple system
figure 1-1 Simple systems with one sensor
1.2 Interfaces
1.2.1 USB interface
The USB interface of the DIQ/S 281 provides the following functions:
Connection of a USB memory device to carry out a software update (see
section 4.11)
Connection of a USB memory device to be used as an electronic key for sim-
ple access to the system when access control is switched on (see
section 5.3.3)
Connection of a USB hub for the reproduction of the USB interface.
Note:
The USB interface is designed for USB memory devices with a maximum power
consumption of 1 watt. USB memory devices with a higher power consumption
have to be supplied with power by an extra power supply. If these instructions
are not complied with, the availability of the system can be adversely affected.
DIQ/JBDIQ/JB
Universal transmitter
DIQ/S 281CR2
IQ sensor, digital

Overview DIQ/S 281
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10
1.2.2 Fieldbus interface (DIQ/S 281-MOD)
The following variants of the DIQ/S 281 have a fieldbus interface:
1.3 Behavior of the system to a power failure
The system configuration is permanently retained. It consists of the following
settings:
– Sensor settings
– Settings and links of the relay outputs
– Settings of the current outputs
– System settings (display language, air pressure/altitude, passwords etc.)
Linked relay outputs switch to the non-active condition (open).
Current outputs switch to the non active-condition (0 mA).
A restart is carried out automatically when the power returns. The continues
working with the settings of the time prior to the power failure.
If the power failure lasted several hours the system clock has to be reset.
The USB interface is equipped with a protective cover.
Only remove the protective cover when you want to connect a USB
device. Immediately close the USB connection again when you
have removed the USB device.
When the USB connection is open, there is a danger of corrosion.
DIQ/S 281 variant Fieldbus connection
DIQ/S 281-MOD Modbus RTU/RS 485

DIQ/S 281 Safety
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2 Safety
2.1 Safety information
2.1.1 Safety information in the operating manual
This operating manual provides important information on the safe operation of
the product. Read this operating manual thoroughly and make yourself familiar
with the product before putting it into operation or working with it. The operating
manual must be kept in the vicinity of the product so you can always find the
information you need.
Important safety instructions are highlighted in this operating manual. They are
indicated by the warning symbol (triangle) in the left column. The signal word
(e.g. "CAUTION") indicates the level of danger:
indicates a situation where goods might be damaged if the actions mentioned
are not taken.
2.1.2 Safety signs on the product
Note all labels, information signs and safety symbols on the product. A warning
symbol (triangle) without text refers to safety information in this operating
manual.
2.1.3 Further documents providing safety information
The following documents provide additional information, which you should
observe for your safety when working with the measuring system:
Operating manuals of other components of the measuring system
Safety datasheets of calibration and maintenance equipment (e.g. cleaning
solutions).
WARNING
indicates a possibly dangerous situation that can lead to seri-
ous (irreversible) injury or death if the safety instruction is not
followed.
CAUTION
indicates a possibly dangerous situation that can lead to slight
(reversible) injury if the safety instruction is not followed.

Safety DIQ/S 281
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2.2 Safe operation
2.2.1 Authorized use
The authorized use of the DIQ/S 281 Universal Transmitter consists of its use in
online analysis. Only the operation and running of the sensor according to the
instructions and technical specifications given in this operating manual is autho-
rized (see chapter 9 TECHNICAL DATA). Any other use is considered unautho-
rized.
2.2.2 Requirements for safe operation
Note the following points for safe operation:
The product may only be operated according to the authorized use specified
above.
The product may only be operated under the environmental conditions men-
tioned in this operating manual.
The product may only be supplied with power by the energy sources men-
tioned in this operating manual.
The product may only be opened if this is explicitly described in this operating
manual (example: connecting electrical lines to the terminal strip).
2.2.3 Unauthorized use
The product must not be put into operation if:
it is visibly damaged (e.g. after being transported)
it was stored under adverse conditions for a lengthy period of time (storing
conditions, see chapter 9 TECHNICAL DATA).
2.3 User qualification
Target group The DIQ/S 281 Universal Transmitter was developed for online analysis. Some
maintenance activities, e.g. changing the membrane caps in D.O. sensors,
require the safe handling of chemicals. Thus, we assume that the maintenance
personnel is familiar with the necessary precautions to take when dealing with
chemicals as a result of their professional training and experience.
Special user
qualifications
The following installation activities may only be performed by a qualified electri-
cian:
Connection of the DIQ/S 281 to the power supply.
Connecting external, line voltage-carrying circuits to relay contacts.

DIQ/S 281 Installation
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3Installation
3.1 Scopes of delivery
The following parts are included in the scope of delivery:
Universal transmitter DIQ/S 281
Accessory kit with:
– Contact carrier with screws
– ISO cap nuts with screws and ring washers
– Cable glands with sealing gaskets
Operating manual.
3.2 Basic principles of installation
3.2.1 Requirements of the measurement location
The measurement location must meet the environmental conditions specified in
section 9.1 DIQ/S 281.
Controlled
environmental
conditions
Work on the open instrument (e.g. during mounting, installation, maintenance)
may only be carried out under controlled environmental conditions:
3.3 Safety requirements of the electrical installation
Electrical equipment (such as motors, contactors, cables, lines, relays,
switches, instruments) must meet the following requirements:
Compliance with national regulations (e.g. NEC, VDE and IEC)
Suitability for the electrical conditions at the place of installation
– Maximum operational voltage
– Maximum operational current
Suitability for the ambient conditions at the place of installation
– Temperature resistance (minimum and maximum temperature)
– Stability against UV light in the case of outdoor usage
– Protection against water and dust (IP type of protection).
Suitable fuse protection of the electrical circuit
– Overcurrent protection devices
Temperature + 5 °C ... + 40 °C (+ 41 ... +104 °F)
Relative humidity ≤ 80 %

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14
(according to the technical data of the instrument input or output)
– Overvoltage limitations of overvoltage category II
Suitable external separator (e.g. switch or circuit-breaker) for the power sup-
ply of permanently installed instruments with separate power connection
– compliant with the following regulations
- IEC 60947-1
- IEC 60947-3
– in the vicinity of the instruments (recommendation)
Flame resistant (cable and lines),
compliant with the following regulations
– UL 2556 VW-1 (for USA, Canada)
– IEC 60332-1-2 (outside the USA, Canada)
3.4 Installation guidelines for lightning protection
During the use of the DIQ/S 281 universal transmitter, particularly in outdoor
areas, adequate protection against (electrical) surges must be provided. A surge
is a summation phenomenon of surge voltage and surge current. It is generated
through the indirect effect of a lightning event or switching operation in the
mains, in the grounding system and in information technology lines.
To be adequately protected against the damaging effects of surges, an inte-
grated concept of the following protective measures is required:
internal device-related protective measures and
external protective measures of the installation environment.
The internal device-related protective measures are already integrated in the
YSI online instrumentation as so-called 'lightning protection' (see
chapter 9 TECHNICAL DATA).
The external protective measures of the installation environment can be carried
out with respect to the following guidelines:
1 All lines of systems must be
a) installed inside (or else close to) the grounded metallic mounting construc-
tions, e.g. handrails, pipes and posts if possible
b) or, particularly in the case of longer lines, laid in the ground.
Background: The formation of highly lightning hazardous inductive loops be-
tween the cables and ground is avoided through the low clearance of the
grounded metal construction or by installation in the ground.
2 Only IQ cable material may be used. This cable material is an important pre-
requisite for the hazard-free discharging of the surge without inadmissibly
high overvoltages developing along the line at the same time that could have
a damaging effect on the individual components.
3 All metallic mounting constructions (handrails, pipes, posts etc.) on which

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15
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DIQ modules are installed must be connected to the local potential equaliza-
tion system and the grounding system or must be individually sufficiently
grounded locally according to the codes of practice.
For the individual grounding of the measuring point the mounting construc-
tion must be solidly connected by means of a large-area auxiliary electrode
with the measuring medium.
Metallic control shafts/pipes and other large-area metallic bodies that reach
into the measuring medium are, for example, ideal for use in the grounding
of the mounting construction.
This creates a set path for the main surge. As a result it is possible to avoid
the surge being discharged via the cable and via the valuable sensor in the
measuring medium.
4 It is recommended to attach a metallic or nonmetallic sun shield to each out-
side location of the DIQ modules. Sun shields protect the electric field lines
in the area of the DIQ module due to an advantageous development of the
electrical field lines in the area of the MIQ module and promote the dissipa-
tion of the surge via the mounting construction.
5 The line voltage for the supply of the DIQ/S 281 must comply with overvolt-
age category II. Generally this is ensured through the public operator of the
power supply networks. In company-owned networks, e.g. in all power supply
systems owned by wastewater treatment plants, this must be kept separate
by a potential equalization and a surge protection system for the plant.
6 Part of the safety and lightning protection concept is based on the high-qual-
ity protective insulation of the DIQ/S 281. It does not have or require a pro-
tective earth or ground connection. Avoid any direct contact of any SENSOR
connections or the metallic sensor enclosures with the local grounding or po-
tential equalization system and with metallic construction elements (see point
8).
7 Additional external lightning protection measures, e.g. the use of overvoltage
surge arresters, are not necessary for protection against the indirect effects
of lightning and could possibly result in malfunctions.
8 For the realization of the internal lightning protection of the system (e.g.
wastewater treatment plant control stands) and for the protection of external
resources, cable entry points into buildings or distributions coming from the
DIQ/S 281 must be carried out as follows:
– The shield of SNCIQ or SNCIQ-UG cables can be connected to the local
potential equalization with a gas overvoltage arrester. Use shield clamps
for the contacting of the shield. The shield of the cable must not be opened
under any circumstances.
– 0/4-20 mA interfaces must be realized with shielded cables. The cable
shield must be connected directly to the potential equalization(s) provided.
If plant potential equalization systems are provided on both sides, the
shield must also be connected on both sides. The inner conductors must
have no contact with the potential equalization.
– Relay lines should be connected to the local potential equalization in order
to provide general and consistent protection via gas overvoltage surge

Installation DIQ/S 281
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16
arresters.
3.5 Connecting system components
3.5.1 General information
The IQ SENSORNET system components are connected to form a functioning
unit in the following ways:
Stacked mounting of MIQ modules
Up to three MIQ modules can be installed and mechanically connected with
one another to form a stack at a single location. The contacts on the front and
rear automatically create the electrical connection between the MIQ modules
in the stack (section 3.5.2).
Distributed mounting of MIQ modules
Individual MIQ modules or an assembled module stack are installed at vari-
ous locations (for example, a central control unit and an MIQ branching mod-
ule for connecting IQ sensors at the edge of the basin). The spatial distance
is bridged with the aid of the SNCIQ or SNCIQ/UG cable (section 3.5.3).
Connection of IQ sensors:
IQ sensors are connected to an MIQ module with the aid of the SACIQ cable.
This cable is available in different lengths. The MIQ module must have a free
SENSORNET connection on the terminal strip. On the sensor side, the con-
nection is made with a plug that is standard for all IQ sensors (section 3.5.4).
The connection of the system components is described in the fol-
lowing sections exclusively with examples of the connection of MIQ
modules.
These descriptions similarly apply to system components that are
not mentioned separately in the examples (e.g. universal transmitter
DIQ/S 281).
Distributed mounting is only allowed in a star configuration. The
system must nowhere be closed to form a ring. Only use the
assembly material provided for the installation.

DIQ/S 281 Installation
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3.5.2 Stacked mounting of DIQ and MIQ modules
Mounting direction MIQ modules can be stacked on top of one another from both sides. All the
required installation materials are contained in the scope of delivery of the
MIQ modules.
Which variant is suitable for a specific case depends on whether and how an
MIQ module is already permanently installed at a location (e.g. on a wall or in a
panel), among other factors.
Materials required 2 x ISO blind nuts (M4)
2 x cheese-head screws (M4x16) with plastic washer
1 x contact base with two plastic tapping screws.
Tools Phillips screwdriver.
Both installation variants are described below. To dismantle a module stack,
proceed in the reverse order to mounting the stack.
For optimum stability, a maximum of three modules (DIQ/MIQ) can
be mounted in any one stack. Only one MIQ power supply module
may be mounted per module stack.
Variant 1 - stack expansion forwards.
The back of an MIQ module is
attached to the lid of another
MIQ module (see page 18).
Variant 2: - stack expansion
backwards.
The lid of an MIQ module is attached
to the back of another MIQ module
(see page 22).
In the case of panel mounting, the front MIQ module can only be
installed individually in the switch cabinet aperture. Only then can
further MIQ modules be added to its back (variant 2). If necessary,
dismantle the front MIQ module from an already mounted stack
before mounting.

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Variant 1: Stack expansion forwards
Preparing the
stack mounting
figure 3-1 Preparing MIQ modules for stack mounting (variant 1)
1 Covers of the drilled mounting holes (rear MIQ module)
2 Contact cover (rear MIQ module )
3 Covers of the drilled mounting holes (front MIQ module)
4 Label (front MIQ module)
1 Remove the covers from the drilled mounting holes (pos. 1 and 3 in
figure 3-1).
2 Remove the contact cover (pos. 2).
3 Pull off the adhesive label (pos. 4).
Bei Stapelmontage Aufkleber
entfernen und Kontaktträger
montieren
For stack mounting remove label
and install contact carrier
13
24

DIQ/S 281 Installation
19
ba76226e02 03/2023
Mounting the
contact base
figure 3-2 Mounting the contact base (variant 1)
5 Contact base
6 Tapping screws
7 Countersunk screws
Only IQ Sensor Net products may be used in the IQ Sensor Net.
4 Attach the contact base (pos. 5 in figure 3-2) on the front MIQ module
with the two plastic tapping screws (pos. 6).
5 On the front MIQ module, remove the two countersunk screws (pos. 7
in figure 3-2) and swing open the module lid.
7
5
6

Installation DIQ/S 281
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20
Premounting the
ISO blind nuts
Stacking the
MIQ modules
figure 3-3 Mounting the contact base (variant 1)
8 Cheese-head screws
9 ISO blind nuts
6 Insert the cheese-head screws (pos. 8 in figure 3-2) with the plastic
washers in the drilled mounting holes in the enclosure and loosely
screw in the ISO blind nuts (pos. 9).
9
8
figure 3-4 Stacking the MIQ modules (variant 1)