Campbell Scientific CR6 User's Guide

Revision: 01/27/2021
Copyright © 2000 – 2021
Campbell Scientific, Inc.

Table of Contents

1. CR6 data acquisition system components 1
1.1 The CR6 Datalogger 2
1.1.1 Overview 2
1.1.2 Communications Options 2
1.1.3 Operations 3
1.1.4 Programs 3
1.2 Sensors 3
2. Wiring panel and terminal functions 5
2.1 Power input 8
2.1.1 Powering a data logger with a vehicle 10
2.1.2 Power LED indicator 10
2.2 Power output 10
2.3 Grounds 11
2.4 Communications ports 13
2.4.1 USB device port 13
2.4.2 Ethernet port 13
2.4.3 C and U terminals for communications 13
2.4.4 CS I/O port 15
2.4.5 RS-232/CPI port 16
2.5 Programmable logic control 17
3. Setting up the CR6 19
3.1 Setting up communications with the data logger 19
3.1.1 USB or RS-232 communications 20
3.1.2 Virtual Ethernet over USB (RNDIS) 21
3.1.3 Ethernet communications option 22
3.1.3.1 Configuring data logger Ethernet settings 23
Table of Contents - i
3.1.3.3 Setting up Ethernet communications between the data logger and computer 24
3.1.4 Wi-Fi communications option 25
3.1.4.1 Configuring the data logger to host a Wi-Fi network 25
3.1.4.2 Connecting your computer to the data logger over Wi-Fi 26
3.1.4.3 Setting up Wi-Fi communications between the data logger and the data logger support software 26
3.1.4.4 Configuring data loggers to join a Wi-Fi network 27
3.1.4.5 Wi-Fi LED indicator 28
3.1.5 Radio communications option 28
3.1.5.1 Configuration options 29
3.1.5.2 RF407-Series radio communications with one or more data loggers 30 Configuring the RF407-Series radio 30 Setting up communications between the RF407-Series data logger and the computer 31
3.1.5.3 RF407-Series radio communications with multiple data loggers using one
data logger as a router 32
Configuring the RF407-Series radio 33 Configuring the data logger acting as a router 33
Adding routing data logger to LoggerNet network 34 Adding leaf data loggers to the network 35
Using additional communications methods 35
3.1.5.4 RF451 radio communications with one or more dataloggers 35 Configuring the RF451 radio connected to the computer 36 Configuring slave RF451 dataloggers 36 Setting up communications between the RF451 data logger and the computer37
3.1.5.5 RF451 radio communications with multiple dataloggers using one data
logger as a repeater 38
Configuring the RF451 radio connected to the computer 39 Configuring the data logger acting as a repeater 39 Adding the repeater data logger to the LoggerNet network 40 Adding leaf dataloggers to the network 40 Using additional communication methods 41
3.2 Testing communications with EZSetup 41
3.3 Making the software connection 43
3.4 Creating a Short Cut data logger program 43
3.5 Sending a program to the data logger 46
Table of Contents - ii
4. Working with data 48
4.1 Default data tables 48
4.2 Collecting data 49
4.2.1 Collecting data using LoggerNet 49
4.2.2 Collecting data using PC200W or PC400 49
4.3 Viewing historic data 50
4.4 Data types and formats 50
4.4.1 Variables 51
4.4.2 Constants 52
4.4.3 Data storage 53
4.5 About data tables 54
4.5.1 Table definitions 54
4.5.1.1 Header rows 55
4.5.1.2 Data records 56
4.6 Creating data tables in a program 57
5. Data memory 59
5.1 Data tables 59
5.2 Memory allocation 59
5.3 SRAM 60
5.3.1 USRdrive 61
5.4 Flash memory 62
5.4.1 CPU drive 62
5.5 MicroSD (CRD:drive) 62
5.5.1 Formatting microSD cards 63
5.5.2 MicroSDcard precautions 63
5.5.3 Act LED indicator 64
6. Measurements 65
6.1 Voltage measurements 65
6.1.1 Single-ended measurements 66
6.1.2 Differential measurements 67
6.1.2.1 Reverse differential 67
6.2 Current-loop measurements 67
6.2.1 Example Current-Loop Measurement Connections 68
6.3 Resistance measurements 70
6.3.1 Resistance measurements with voltage excitation 71
Table of Contents - iii
6.3.2 Resistance measurements with current excitation 73
6.3.3 Strain measurements 75
6.3.4 AC excitation 77
6.3.5 Accuracy for resistance measurements 78
6.4 Period-averaging measurements 78
6.5 Pulse measurements 79
6.5.1 Low-level AC measurements 81
6.5.2 High-frequency measurements 81
6.5.2.1 U terminals 82
6.5.2.2 C terminals 82
6.5.3 Switch-closure and open-collector measurements 82
6.5.3.1 U Terminals 82
6.5.3.2 C terminals 83
6.5.4 Edge timing and edge counting 83
6.5.4.1 Single edge timing 83
6.5.4.2 Multiple edge counting 83
6.5.4.3 Timer input NAN conditions 84
6.5.5 Quadrature measurements 84
6.5.6 Pulse measurement tips 85
6.5.6.1 Input filters and signal attenuation 85
6.5.6.2 Pulse count resolution 86
6.6 Vibrating wire measurements 86
6.6.1 VSPECT® 87
6.6.1.1 VSPECT diagnostics 87 Decay ratio 87 Signal-to-noise ratio 87 Low signal strength amplitude warning 88
6.6.2 Improving vibrating wire measurement quality 88
6.6.2.1 Matching measurement ranges to expected frequencies 88
6.6.2.2 Rejecting noise 88
6.6.2.3 Minimizing resonant decay 88
6.6.2.4 Preventing spectral leakage 89
6.7 Sequential and pipeline processing modes 89
6.7.1 Sequential mode 89
6.7.2 Pipeline mode 90
6.7.3 Slow Sequences 90
Table of Contents - iv
7. Communications protocols 91
7.1 General serial communications 92
7.1.1 RS-232 94
7.1.2 RS-485 95
7.1.3 RS-422 96
7.1.4 TTL 97
7.1.5 LVTTL 97
7.1.6 TTL-Inverted 97
7.1.7 LVTTL-Inverted 98
7.2 Modbus communications 98
7.2.1 About Modbus 99
7.2.2 Modbus protocols 100
7.2.3 Understanding Modbus Terminology 101
7.2.4 Connecting Modbus devices 101
7.2.5 Modbus master-slave protocol 102
7.2.6 About Modbus programming 102
7.2.6.1 Endianness 103
7.2.6.2 Function codes 103
7.2.7 Modbus information storage 104
7.2.7.2 Coils 105
7.2.7.3 Data Types 105 Unsigned 16-bit integer 105 Signed 16-bit integer 106 Signed 32-bit integer 106 Unsigned 32-bit integer 106 32-Bit floating point 106
7.2.8 Modbus tips and troubleshooting 106
7.2.8.1 Error codes 107 Result code -01: illegal function 107 Result code -02: illegal data address 107 Result code -11: COM port error 107
7.3 Internet communications 108
7.3.1 IPaddress 108
7.3.2 HTTPS server 108
7.3.3 FTP server 109
7.4 DNP3 communications 110
Table of Contents - v
7.5 Serial peripheral interface (SPI) and I2C 110
7.6 PakBus communications 111
7.7 SDI-12 communications 111
7.7.1 SDI-12 transparent mode 112
7.7.1.1 Watch command (sniffer mode) 113
7.7.1.2 SDI-12 transparent mode commands 114
7.7.1.3 aXLOADOS! command 114
7.7.2 SDI-12 programmed mode/recorder mode 116
7.7.3 Programming the data logger to act as an SDI-12 sensor 116
7.7.4 SDI-12 power considerations 117
8. CR6 maintenance 119
8.1 Data logger calibration 119
8.1.1 About background calibration 120
8.2 Data logger security 121
8.2.1 TLS 122
8.2.2 Security codes 122
8.2.3 Creating a .csipasswd file 123
8.2.3.1 Command syntax 125
8.3 Data logger enclosures 125
8.4 Internal battery 126
8.4.1 Replacing the internal battery 127
8.5 Electrostatic discharge and lightning protection 128
8.6 Power budgeting 130
8.7 Updating the operating system 131
8.7.1 Sending an operating system to a local data logger 131
8.7.2 Sending an operating system to a remote data logger 132
8.8 File management via powerup.ini 133
8.8.1 Syntax 134
8.8.2 Example powerup.ini files 135
9. Tips and troubleshooting 137
9.1 Checking station status 138
9.1.1 Viewing station status 139
9.1.2 Watchdog errors 139
9.1.3 Results for last program compiled 140
9.1.4 Skipped scans 140
9.1.5 Skipped records 140
Table of Contents - vi
9.1.6 Variable out of bounds 140
9.1.7 Battery voltage 140
9.2 Understanding NAN and INF occurrences 140
9.3 Timekeeping 141
9.3.1 Clock best practices 142
9.3.2 Time stamps 142
9.3.3 Avoiding time skew 143
9.4 CRBasic program errors 143
9.4.1 Program does not compile 144
9.4.2 Program compiles but does not run correctly 144
9.5 Troubleshooting Radio Communications 145
9.6 Resetting the data logger 145
9.6.1 Processor reset 145
9.6.2 Program send reset 145
9.6.3 Manual data table reset 146
9.6.4 Formatting drives 146
9.6.5 Full memory reset 146
9.7 Troubleshooting power supplies 147
9.8 Using terminal mode 147
9.8.1 Serial talk through and comms watch 150
9.8.2 SDI-12 transparent mode 150
9.8.2.1 Watch command (sniffer mode) 151
9.8.2.2 SDI-12 transparent mode commands 152
9.9 Ground loops 152
9.9.1 Common causes 153
9.9.2 Detrimental effects 153
9.9.3 Severing a ground loop 155
9.9.4 Soil moisture example 156
9.10 Improving voltage measurement quality 157
9.10.1 Deciding between single-ended or differential measurements 157
9.10.2 Minimizing ground potential differences 158
9.10.2.1 Ground potential differences 159
9.10.3 Detecting open inputs 159
9.10.4 Minimizing power-related artifacts 160
9.10.4.1 Minimizing electronic noise 161
9.10.5 Filtering to reduce measurement noise 162
9.10.5.1 CR6 filtering details 162
Table of Contents - vii
9.10.6 Minimizing settling errors 163
9.10.6.1 Measuring settling time 163
9.10.7 Factors affecting accuracy 165
9.10.7.1 Measurement accuracy example 166
9.10.8 Minimizing offset voltages 166
9.10.8.1 Compensating for offset voltage 168
9.10.8.2 Measuring ground reference offset voltage 169
9.11 Field calibration 170
9.12 File system error codes 171
9.13 File name and resource errors 172
9.14 Background calibration errors 172
10. Information tables and settings (advanced) 173
10.1 DataTableInfo table system information 174
10.1.1 DataFillDays 174
10.1.2 DataRecordSize 174
10.1.3 DataTableName 174
10.1.4 RecNum 174
10.1.5 SecsPerRecord 175
10.1.6 SkippedRecord 175
10.1.7 TimeStamp 175
10.2 Status table system information 175
10.2.1 Battery 175
10.2.2 BuffDepth 175
10.2.3 CalCurrent 175
10.2.4 CalGain 176
10.2.5 CalOffset 176
10.2.6 CalRefOffset 176
10.2.7 CalRefSlope 176
10.2.8 CalVolts 176
10.2.9 CardStatus 176
10.2.10 ChargeInput 176
10.2.11 ChargeState 176
10.2.12 CommsMemFree 176
10.2.13 CompileResults 177
10.2.14 ErrorCalib 177
10.2.15 FullMemReset 177
Table of Contents - viii
10.2.16 IxResistor 177
10.2.17 LastSystemScan 177
10.2.18 LithiumBattery 177
10.2.19 Low12VCount 177
10.2.20 MaxBuffDepth 177
10.2.21 MaxProcTime 178
10.2.22 MaxSystemProcTime 178
10.2.23 MeasureOps 178
10.2.24 MeasureTime 178
10.2.25 MemoryFree 178
10.2.26 MemorySize 178
10.2.27 Messages 178
10.2.28 OSDate 179
10.2.29 OSSignature 179
10.2.30 OSVersion 179
10.2.31 PakBusRoutes 179
10.2.32 PanelTemp 179
10.2.33 PortConfig 179
10.2.34 PortStatus 179
10.2.35 PowerSource 180
10.2.36 ProcessTime 180
10.2.37 ProgErrors 180
10.2.38 ProgName 180
10.2.39 ProgSignature 180
10.2.40 RecNum 180
10.2.41 RevBoard 180
10.2.42 RunSignature 181
10.2.43 SerialNumber 181
10.2.44 SkippedScan 181
10.2.45 SkippedSystemScan 181
10.2.46 StartTime 181
10.2.47 StartUpCode 181
10.2.48 StationName 181
10.2.49 SW12Volts 182
10.2.50 SystemProcTime 182
10.2.51 TimeStamp 182
10.2.52 VarOutOfBound 182
Table of Contents - ix
10.2.53 WatchdogErrors 182
10.2.54 WiFiUpdateReq 182
10.3 CPIStatus system information 182
10.3.1 BusLoad 183
10.3.2 ModuleReportCount 183
10.3.3 ActiveModules 183
10.3.4 BuffErr (buffer error) 183
10.3.5 RxErrMax 183
10.3.6 TxErrMax 184
10.3.7 FrameErr (frame errors) 184
10.3.8 ModuleInfo array 184
10.4 Settings 184
10.4.1 Baudrate 185
10.4.2 Beacon 185
10.4.3 CentralRouters 185
10.4.4 CommsMemAlloc 186
10.4.5 ConfigComx 186
10.4.6 CSIOxnetEnable 186
10.4.7 CSIOInfo 187
10.4.8 DisableLithium 187
10.4.9 DeleteCardFilesOnMismatch 187
10.4.10 DNS 187
10.4.11 EthernetInfo 187
10.4.12 EthernetPower 188
10.4.13 FilesManager 188
10.4.14 FTPEnabled 188
10.4.15 FTPPassword 188
10.4.16 FTPPort 188
10.4.17 FTPUserName 188
10.4.18 HTTPEnabled 188
10.4.19 HTTPHeader 189
10.4.20 HTTPPort 189
10.4.21 HTTPSEnabled 189
10.4.22 HTTPSPort 189
10.4.23 IncludeFile 189
10.4.24 IPAddressCSIO 189
10.4.25 IPAddressEth 190
Table of Contents - x
10.4.26 IPGateway 190
10.4.27 IPGatewayCSIO 190
10.4.28 IPMaskCSIO 190
10.4.29 IPMaskEth 190
10.4.30 IPMaskWiFi 191
10.4.31 IPTrace 191
10.4.32 IPTraceCode 191
10.4.33 IPTraceComport 191
10.4.34 IsRouter 191
10.4.35 MaxPacketSize 191
10.4.36 Neighbors 192
10.4.37 NTPServer 192
10.4.38 PakBusAddress 192
10.4.39 PakBusEncryptionKey 192
10.4.40 PakBusNodes 192
10.4.41 PakBusPort 193
10.4.42 PakBusTCPClients 193
10.4.43 PakBusTCPEnabled 193
10.4.44 PakBusTCPPassword 193
10.4.45 PingEnabled 193
10.4.46 PCAP 193
10.4.47 pppDial 194
10.4.48 pppDialResponse 194
10.4.49 pppInfo 194
10.4.50 pppInterface 194
10.4.51 pppIPAddr 194
10.4.52 pppPassword 195
10.4.53 pppUsername 195
10.4.54 RouteFilters 195
10.4.55 RS232Handshaking 195
10.4.56 RS232Power 195
10.4.57 RS232Timeout 196
10.4.58 Security(1), Security(2), Security(3) 196
10.4.59 ServicesEnabled 196
10.4.60 TCPClientConnections 196
10.4.61 TCP_MSS 196
10.4.62 TCPPort 196
Table of Contents - xi
10.4.63 TelnetEnabled 196
10.4.64 TLSConnections (Max TLS Server Connections) 196
10.4.65 TLSPassword 197
10.4.66 TLSStatus 197
10.4.67 UDPBroadcastFilter 197
10.4.68 USBEnumerate 197
10.4.69 USRDriveFree 197
10.4.70 USRDriveSize 197
10.4.71 UTCOffset 198
10.4.72 Verify 198
10.4.73 RF407-series radio settings 198
10.4.73.1 RadioAvailFreq 198
10.4.73.2 RadioChanMask 199
10.4.73.3 RadioEnable 199
10.4.73.4 RadioHopSeq 199
10.4.73.5 RadioMAC 199
10.4.73.6 RadioModel 199
10.4.73.7 RadioModuleVer 200
10.4.73.8 RadioNetID 200
10.4.73.9 RadioProtocol 200
10.4.73.10 RadioPwrMode 201
10.4.73.11 RadioRetries 201
10.4.73.12 RadioRSSI 202
10.4.73.13 RadioRSSIAddr 202
10.4.73.14 RadioStats 202
10.4.73.15 RadioTxPwr 203
10.4.74 RF451 radio settings 203
10.4.74.1 RadioCarrier 203
10.4.74.2 RadioDataRate 204
10.4.74.3 RadioDiag 204
10.4.74.4 RadioEnable 204
10.4.74.5 RadioFirmwareVer 204
10.4.74.6 RadioFreqKey 205
10.4.74.7 RadioFreqRepeat 205
10.4.74.8 RadioFreqZone 205
10.4.74.9 RadioHopSize 206
10.4.74.10 RadioHopVersion 206
Table of Contents - xii
10.4.74.11 RadioLowPwr 207
10.4.74.12 RadioMaxPacket 207
10.4.74.13 RadioMinPacket 208
10.4.74.14 RadioMMSync 208
10.4.74.15 RadioModOS 208
10.4.74.16 RadioModuleVer 208
10.4.74.17 RadioNetID 209
10.4.74.18 RadioOpMode 209
10.4.74.19 RadioPacketRepeat 210
10.4.74.20 RadioRepeaters 211
10.4.74.21 RadioRetryOdds 211
10.4.74.22 RadioRetryTimeout 212
10.4.74.23 RadioRxSubID 212
10.4.74.24 RadioSlaveRepeat 213
10.4.74.28 RadioTxSubID 215
10.4.75 Wi-Fi settings 215
10.4.75.1 IPAddressWiFi 216
10.4.75.2 IPGatewayWiFi 216
10.4.75.3 IPMaskWiFi 216
10.4.75.4 WiFiChannel 216
10.4.75.5 WiFiConfig 217
10.4.75.6 WiFiEAPMethod 217
10.4.75.7 WiFiEAPPassword 217
10.4.75.8 WiFiEAPUser 217
10.4.75.9 Networks 217
10.4.75.10 WiFiEnable 217
10.4.75.11 WiFiFwdCode (Forward Code) 218
10.4.75.12 WiFiPassword 218
10.4.75.13 WiFiPowerMode 218
10.4.75.14 WiFiSSID (Network Name) 218
10.4.75.15 WiFiStatus 219
10.4.75.16 WiFiTxPowerLevel 219
10.4.75.17 WLANDomainName 219
Table of Contents - xiii
11. CR6 Specifications 220
11.1 System specifications 220
11.2 Physical specifications 221
11.3 Power requirements 221
11.4 Power output specifications 223
11.4.1 System power out limits (when powered with 12VDC) 223
11.4.2 12 V and SW12 V power output terminals 224
11.4.3 U and C as power output 224
11.4.4 CSI/O pin 1 225
11.4.5 Voltage and current excitation specifications 225
11.4.5.1 Voltage excitation 225
11.4.5.2 Current excitation 225
11.5 Analog measurement specifications 226
11.5.1 Voltage measurements 226
11.5.2 Resistance measurement specifications 228
11.5.3 Period-averaging measurement specifications 229
11.5.4 Static vibrating wire measurement specifications 229
11.5.5 Thermistor measurement specifications 230
11.5.6 Current-loop measurement specifications 230
11.6 Pulse measurement specifications 231
11.6.1 Switch closure input 231
11.6.2 High-frequency input 232
11.6.3 Low-level AC input 232
11.7 Digital input/output specifications 232
11.7.1 Switch closure input 233
11.7.2 High-frequency input 233
11.7.3 Edge timing 233
11.7.4 Edge counting 234
11.7.5 Quadrature input 234
11.7.6 Pulse-width modulation 234
11.8 Communications specifications 234
11.8.1 Wi-Fi option specifications 235
11.8.2 RF radio option specifications 236
11.9 Standards compliance specifications 237
Appendix A. Glossary 239
Table of Contents - xiv

1. CR6 data acquisition system components

A basic data acquisition system consists of sensors, measurement hardware, and a computer with programmable software. The objective of a data acquisition system should be high accuracy, high precision, and resolution as high as appropriate for a given application.
The components of a basic data acquisition system are shown in the following figure.
Following is a list of typical data acquisition system components:
l Sensors - Electronic sensors convert the state of a phenomenon to an electrical signal (see
Sensors (p. 3) for more information).
l Data logger - The data logger measures electrical signals or reads serial characters. It
converts the measurement or reading to engineering units, performs calculations, and reduces data to statistical values. Data is stored in memory to await transfer to a computer by way of an external storage device or a communications link.
l Data Retrieval and Communications - Data is copied (not moved) from the data logger,
usually to a computer, by one or more methods using data logger support software. Most communications options are bi-directional, which allows programs and settings to be sent
1. CR6 data acquisition system components 1
to the data logger. For more information, see Sending a program to the data logger (p.
46).
l Datalogger Support Software - Software retrieves data, sends programs, and sets settings.
The software manages the communications link and has options for data display.
l Programmable Logic Control - Some data acquisition systems require the control of
external devices to facilitate a measurement or to control a device based on measurements. This data logger is adept at programmable logic control. See Programmable logic control (p. 17) for more information.
l Measurement and Control Peripherals - Sometimes, system requirements exceed the
capacity of the data logger. The excess can usually be handled by addition of input and output expansion modules.

1.1 The CR6 Datalogger

The CR6 data logger provides fast communications, low power requirements, built-in USB, compact size and and high analog input accuracy and resolution. It includes universal (U) terminals, which allow connection to virtually any sensor - analog, digital, or smart. This multipurpose data logger is also capable of doing static vibrating-wire measurements.

1.1.1 Overview

The CR6 data logger is the main part of a data acquisition system (see CR6 data acquisition
system components (p. 1) for more information). It has a central-processing unit (CPU), analog
and digital measurement inputs, analog and digital outputs, and memory. An operating system (firmware) coordinates the functions of these parts in conjunction with the onboard clock and the CRBasic application program.
The CR6 can simultaneously provide measurement and communications functions. Low power consumption allows the data logger to operate for extended time on a battery recharged with a solar panel, eliminating the need for ac power. The CR6 temporarily suspends operations when primary power drops below 9.6 V, reducing the possibility of inaccurate measurements.

1.1.2 Communications Options

The CR6 can include Wi-Fi or the following radio options for different regions:
l RF407: 900 MHz (United States and Canada) l RF412: 920 MHz (Australia and New Zealand) l RF422: 868 MHz (Europe) l RF451: 900 MHz, 1 Watt (United States, Canada, and Australia)
1. CR6 data acquisition system components 2

1.1.3 Operations

The CR6 measures almost any sensor with an electrical response, drives direct communications and telecommunications, reduces data to statistical values, performs calculations, and controls external devices. After measurements are made, data is stored in onboard, nonvolatile memory. Because most applications do not require that every measurement be recorded, the program usually combines several measurements into computational or statistical summaries, such as averages and standard deviations.

1.1.4 Programs

A program directs the data logger on how and when sensors are measured, calculations are made, data is stored, and devices are controlled. The application program for the CR6 is written in CRBasic, a programming language that includes measurement, data processing, and analysis routines, as well as the standard BASIC instruction set. For simple applications, Short Cut, a user­friendly program generator, can be used to generate the program. For more demanding programs, use the full featured CRBasic Editor.
Programs are run by the CR6 in either sequential mode or pipeline mode. In sequential mode, each instruction is executed sequentially in the order it appears in the program. In pipeline mode, the CR6 determines the order of instruction execution to maximize efficiency.

1.2 Sensors

Sensors transduce phenomena into measurable electrical forms by modulating voltage, current, resistance, status, or pulse output signals. Suitable sensors do this with accuracy and precision. Smart sensors have internal measurement and processing components and simply output a digital value in binary, hexadecimal, or ASCII character form.
Most electronic sensors, regardless of manufacturer, will interface with the data logger. Some sensors require external signal conditioning. The performance of some sensors is enhanced with specialized input modules. The data logger, sometimes with the assistance of various peripheral devices, can measure or read nearly all electronic sensor output types.
The following list may not be comprehensive. A library of sensor manuals and application notes is available at www.campbellsci.com/support to assist in measuring many sensor types.
l Analog
o
Voltage
o
Current
o
Strain
1. CR6 data acquisition system components 3
o
Thermocouple
o
Resistive bridge
l Pulse
o
High frequency
o
Switch-closure
o
Low-level ac
o
Quadrature
l Period average l Vibrating wire l Smart sensors
o
SDI-12
o
RS-232
o
Modbus
o
DNP3
o
TCP/IP
o
RS-422
o
RS-485
1. CR6 data acquisition system components 4

2. Wiring panel and terminal functions

The CR6 wiring panel provides ports and removable terminals for connecting sensors, power, and communications devices. It is protected against surge, over-voltage, over-current, and reverse power. The wiring panel is the interface to most data logger functions so studying it is a good way to get acquainted with the data logger. Functions of the terminals are broken down into the following categories:
l Analog input l Pulse counting l Analog output l Communications l Digital I/O l Power input l Power output l Power ground l Signal ground
2. Wiring panel and terminal functions 5
Table 2-1: Analog input terminal functions
U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 RG
Single-Ended Voltage
Differential Voltage H L H L H L H L H L H L
Ratiometric/Bridge
Vibrating Wire (Static,
VSPECT®)
Vibrating Wire with
Thermistor
Thermistor
Thermocouple
Current Loop
Period Average
Table 2-2: Pulse counting terminal functions
U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 C1-C4
Switch-Closure
High Frequency
Low-level Ac
NOTE: Conflicts can occur when a control port pair is used for different instructions (TimerInput(),
PulseCount(), SDI12Recorder(), WaitDigTrig()). For example, if C1 is used for SDI12Recorder(), C2 cannot be used for TimerInput(), PulseCount(), or WaitDigTrig().
Table 2-3: Analog output terminal functions
U1-U12
Switched Voltage Excitation
Switched Current Excitation
2. Wiring panel and terminal functions 6
Table 2-4: Voltage output terminal functions
U1-U12 C1-C4 12V SW12-1 SW12-2
3.3 VDC
5 VDC
12 VDC
C and even numbered U terminals have limited drive capacity. Voltage levels are configured in pairs.
Table 2-5: Communications terminal functions
U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 C1 C2 C3 C4
SDI-12
GPS
Time
Sync
PPS Rx Tx Rx Tx Rx
RS-
232/
CPI
TTL
Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx
0-5 V
LVTTL
Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx Tx Rx
0-3.3 V
RS-232 Tx Rx Tx Rx
RS-485
(Half
Duplex)
RS-485
(Full
Duplex)
I2C SCL SDA SCL SDA SCL SDA SCL SDA SCL SDA SCL SDA SCL SDA SCL SDA
SPI MOSI SCLK MISO MOSI SCLK MISO MOSI SCLK MISO MOSI SCLK MISO
A- B+ A- B+
Tx- Tx+ Rx- Rx+
2. Wiring panel and terminal functions 7
Table 2-5: Communications terminal functions
U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 C1 C2 C3 C4
SDM Data Clk Enabl Data Clk Enabl Data Clk Enabl Data Clk Enabl
RS-
232/
CPI
CPI/
CDM
Table 2-6: Digital I/O terminal functions
U1-U12 C1-C4
General I/O
Pulse-Width Modulation Output
Timer Input
Interrupt
Quadrature

2.1 Power input

The data logger requires a power supply. It can receive power from a variety of sources, operate for several months on non-rechargeable batteries, and supply power to many sensors and devices. The data logger operates with external power connected to the green BAT and/or CHG terminals on the face of the wiring panel. The positive power wire connects to +. The negative wire connects to -. The power terminals are internally protected against polarity reversal and high voltage transients.
In the field, the data logger can be powered in any of the following ways:
l 10 to 18 VDC applied to the BAT + and – terminals l 16 to 32 VDC applied to the CHG + and – terminals
To establish an uninterruptible power supply (UPS), connect the primary power source (often a transformer, power converter, or solar panel) to the CHG terminals and connect a nominal 12 VDC sealed rechargeable lead-acid battery to the BAT terminals. See Power budgeting (p. 130) for more information. The Status Table ChargeState may display any of the following:
2. Wiring panel and terminal functions 8
l No Charge - The charger input voltage is either less than +9.82V±2% or there is no charger
attached to the terminal block.
l Low Charge Input – The charger input voltage is less than the battery voltage. l Current Limited – The charger input voltage is greater than the battery voltage AND the
battery voltage is less than the optimal charge voltage. For example, on a cloudy day, a solar panel may not be providing as much current as the charger would like to use.
l Float Charging – The battery voltage is equal to the optimal charge voltage. l Regulator Fault - The charging regulator is in a fault condition.
WARNING: Sustained input voltages in excess of 32 VDC on CHGor BAT terminals can damage the transient voltage suppression.
Ensure that power supply components match the specifications of the device to which they are connected. When connecting power, switch off the power supply, insert the connector, then turn the power supply on. See Troubleshooting power supplies (p. 147) for more information.
Following is a list of CR6 power input terminals and the respective power types supported.
l BAT terminals: Voltage input is 10 to 18 VDC. This connection uses the least current since
the internal data logger charging circuit is bypassed. If the voltage on the BAT terminals exceeds 19 VDC, power is shut off to certain parts of the data logger to prevent damaging connected sensors or peripherals.
l CHG terminals: Voltage input range is 16 to 32 VDC. Connect a primary power source, such
as a solar panel or VAC-to-VDC transformer, to CHG. The voltage applied to CHG terminals must be at least 0.3 V higher than that needed to charge a connected battery. When within the 16 to 32 VDC range, it will be regulated to the optimal charge voltage for a lead acid battery at the current data logger temperature, with a maximum voltage of approximately 15 VDC. A battery need not be connected to the BAT terminals to supply power to the data logger through the CHG terminals. The onboard charging regulator is designed for efficiently charging lead-acid batteries. It will not charge lithium or alkaline batteries.
l USB port: 5 VDC via USB connection. If power is also provided with BAT or CHG, power will
be supplied by whichever has the highest voltage. If USB is the only power source, then the CS I/O port and the 12V and SW12 terminals will not be operational. When powered by USB (no other power supplies connected) Status field Battery = 0. Functions that will be active with a 5 VDC source include sending programs, adjusting data logger settings, and making some measurements.
2. Wiring panel and terminal functions 9
NOTE: The Status field Battery value and the destination variable from the Battery() instruction (often called batt_volt or BattV) in the Public table reference the external battery voltage. For information about the internal battery, see Internal battery (p. 126).

2.1.1 Powering a data logger with a vehicle

If a data logger is powered by a motor-vehicle power supply, a second power supply may be needed. When starting the motor of the vehicle, battery voltage often drops below the voltage required for data logger operation. This may cause the data logger to stop measurements until the voltage again equals or exceeds the lower limit. A second supply or charge regulator can be provided to prevent measurement lapses during vehicle starting.
In vehicle applications, the earth ground lug should be firmly attached to the vehicle chassis with 12 AWG wire or larger.

2.1.2 Power LED indicator

When the data logger is powered, the Power LED will turn on according to power and program states:
l Off: No power, no program running. l 1 flash every 10 seconds: Powered from BAT, program running. l 2 flashes every 10 seconds: Powered from CHG, program running. l 3 flashes every 10 seconds: Powered via USB, program running. l Always on: Powered, no program running.

2.2 Power output

The data logger can be used as a power source for communications devices, sensors and peripherals. Take precautions to prevent damage to these external devices due to over- or under­voltage conditions, and to minimize errors. Additionally, exceeding current limits causes voltage output to become unstable. Voltage should stabilize once current is again reduced to within stated limits. The following are available:
l 12V: unregulated nominal 12 VDC. This supply closely tracks the primary data logger supply
voltage; so, it may rise above or drop below the power requirement of the sensor or peripheral. Precautions should be taken to minimize the error associated with measurement of underpowered sensors.
2. Wiring panel and terminal functions 10
l SW12: program-controlled, switched 12 VDC terminals. It is often used to power devices
such as sensors that require 12 VDC during measurement. Voltage on a SW12 terminal will change with data logger supply voltage. CRBasic instruction SW12() controls the SW12 terminal. See the CRBasic Editor help for detailed instruction information and program examples: https://help.campbellsci.com/crbasic/cr6/.
l CS I/O port: used to communicate with and often supply power to Campbell Scientific
peripheral devices.
CAUTION: Voltage levels at the 12V and switched SW12 terminals, and pin 8 on the CS I/O port, are tied closely to the voltage levels of the main power supply. Therefore, if the power received at the POWER IN 12V and G terminals is 16 VDC, the 12V and SW12 terminals and pin 8 on the CS I/O port will supply 16 VDC to a connected peripheral. The connected peripheral or sensor may be damaged if it is not designed for that voltage level.
l C or U terminals: can be set low or high as output terminals . With limited drive capacity,
digital output terminals are normally used to operate external relay-driver circuits. Drive current varies between terminals. See also Digital input/output specifications (p. 232).
l U terminals: can be configured to provide regulated ±2500 mV dc excitation.
See also Power output specifications (p. 223).

2.3 Grounds

Proper grounding lends stability and protection to a data acquisition system. Grounding the data logger with its peripheral devices and sensors is critical in all applications. Proper grounding will ensure maximum ESD protection and measurement accuracy. It is the easiest and least expensive insurance against data loss, and often the most neglected. The following terminals are provided for connection of sensor and data logger grounds:
l Signal Ground ( ) - reference for single-ended analog inputs, excitation returns, and a
ground for sensor shield wires.
o
6 common terminals
l Power Ground (G) - return for 3.3 V, 5 V, 12 V, U or C terminals configured for control, and
digital sensors. Use of G grounds for these outputs minimizes potentially large current flow through the analog-voltage-measurement section of the wiring panel, which can cause single-ended voltage measurement errors.
o
4 common terminals
2. Wiring panel and terminal functions 11
l Resistive Ground (RG) - used for non-isolated 0-20 mA and 4-20 mA current loop
measurements (see Current-loop measurements (p. 67) for more information). Also used for decoupling ground on RS-485 signals. Includes 100 Ω resistance to ground. Maximum voltage for RG terminal is ±16 V.
o
1 terminal
l
NOTE: Resistance to ground input for non-isolated 0-20 mA and 4-20 mA current loop measurements is available in CR6 data loggers with serial numbers 7502 and greater. These data loggers have two blue stripes on the label.
l Earth Ground Lug ( ) - connection point for heavy-gage earth-ground wire. A good earth
connection is necessary to secure the ground potential of the data logger and shunt transients away from electronics. Campbell Scientific recommends 14 AWG wire, minimum.
NOTE: Several ground wires can be connected to the same ground terminal.
A good earth (chassis) ground will minimize damage to the data logger and sensors by providing a low-resistance path around the system to a point of low potential. Campbell Scientific recommends that all data loggers be earth grounded. All components of the system (data loggers, sensors, external power supplies, mounts, housings) should be referenced to one common earth ground.
In the field, at a minimum, a proper earth ground will consist of a 5-foot copper-sheathed grounding rod driven into the earth and connected to the large brass ground lug on the wiring panel with a 14 AWG wire. In low-conductive substrates, such as sand, very dry soil, ice, or rock, a single ground rod will probably not provide an adequate earth ground. For these situations, search for published literature on lightning protection or contact a qualified lightning-protection consultant.
In laboratory applications, locating a stable earth ground is challenging, but still necessary. In older buildings, new VAC receptacles on older VAC wiring may indicate that a safety ground exists when, in fact, the socket is not grounded. If a safety ground does exist, good practice dictates to verify that it carries no current. If the integrity of the VAC power ground is in doubt, also ground the system through the building plumbing, or use another verified connection to earth ground.
See also:
l Ground loops (p. 152) l Minimizing ground potential differences (p. 158)
2. Wiring panel and terminal functions 12

2.4 Communications ports

The data logger is equipped with ports that allow communications with other devices and networks, such as:
l Computers l Smart sensors l Modbus and DNP3 networks l Ethernet l Modems l Campbell Scientific PakBus® networks l Other Campbell Scientific data loggers
Campbell Scientific data logger communications ports include:
l CS I/O l RS-232/CPI l USB Device l Ethernet l C and U terminals

2.4.1 USB device port

One USB device port supports communicating with a computer through data logger support software or through virtual Ethernet (RNDIS), and provides 5 VDC power to the data logger (powering through the USB port has limitations - details are available in the specifications). The data logger USB device port does not support USBflash or thumb drives. Although the USB connection supplies 5 V power, a 12 VDC battery will be needed for field deployment.

2.4.2 Ethernet port

The RJ45 10/100 Ethernet port is used for IP communications.

2.4.3 C and U terminals for communications

C and U terminals are configurable for the following communications types:
l SDI-12 l RS-232 l RS-422 l RS-485 l TTL (0 to 5 V)
2. Wiring panel and terminal functions 13
l LVTTL (0 to 3.3 V) l SDM
Some communications types require more than one terminal, and some are only available on specific terminals. This is shown in the data logger specifications.
2.4.3.1 SDI-12 ports
SDI-12 is a 1200 baud protocol that supports many smart sensors. C1, C3, U1, U3, U5, U7, U9, and U11 can each be configured as SDI-12 ports. Maximum cable lengths depend on the number of sensors connected, the type of cable used, and the environment of the application. Refer to the sensor manual for guidance.
For more information, see SDI-12 communications (p. 111).
2.4.3.2 RS-232, RS-422, RS-485, TTL, and LVTTL ports
RS-232, RS-422, RS-485, TTL, and LVTTL communications are typically used for the following:
l Reading sensors with serial output l Creating a multi-drop network l Communications with other data loggers or devices over long cables
Configure C or U terminals as serial ports using Device Configuration Utility or by using the
SerialOpen() CRBasic instruction. C and U terminals are configured in pairs for TTL and
LVTTL communications, and C terminals are configured in pairs for RS-232 or half-duplex RS-422 and RS-485. For full-duplex RS-422 and RS-485, all four C terminals are required. See also
Communications protocols (p. 91).
NOTE: RS-232 ports are not isolated.
2.4.3.3 SDM ports
SDM is a protocol proprietary to Campbell Scientific that supports several Campbell Scientific digital sensor and communications input and output expansion peripherals and select smart sensors. It uses a common bus and addresses each node. CRBasic SDM device and sensor instructions configure terminals C1, C2, and C3 together to create an SDM port. Alternatively, terminals U1, U2, and U3; U5, U6, and U7; or U9, U10, and U11 can be configured together to be used as SDM ports by using the SDMBeginPort() instruction.
See also Communications specifications (p. 234).
2. Wiring panel and terminal functions 14

2.4.4 CS I/O port

One nine-pin port, labeled CS I/O, is available for communicating with a computer through Campbell Scientific communications interfaces, modems, and peripherals. Campbell Scientific recommends keeping CS I/O cables short (maximum of a few feet). See also Communications
specifications (p. 234).
Table 2-7: CS I/O pinout
Pin
Function
Number
1 5 VDC O 5 VDC: sources 5 VDC, used to power peripherals.
2 SG
3 RING I
4 RXD I
5 ME O
6 SDE O
7 CLK/HS I/O
Input(I)
Description
Output(O)
Signal ground: provides a power return for pin 1 (5V), and is used as a reference for voltage levels.
Ring: raised by a peripheral to put the CR6 in the telecom mode.
Receive data: serial data transmitted by a peripheral are received on pin 4.
Modem enable: raised when the CR6 determines that a modem raised the ring line.
Synchronous device enable: addresses synchronous devices (SD); used as an enable line for printers.
Clock/handshake: with the SDE and TXD lines addresses and transfers data to SDs. When not used as a clock, pin 7 can be used as a handshake line; during printer output, high enables, low disables.
8 12VDC
9 TXD O
Nominal 12 VDC power. Same power as 12V and SW12 terminals.
Transmit data: transmits serial data from the data logger to peripherals on pin 9; logic-low marking (0V), logic­high spacing (5V), standard-asynchronous ASCII: eight data bits, no parity, one start bit, one stop bit. User selectable baud rates: 300, 1200, 2400, 4800, 9600, 19200, 38400, 115200.
2. Wiring panel and terminal functions 15
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