- Datasheets
- Accessories
- CB15
- CB25
- CB37 V1.2
- CB37 V2.1
- EB37
- EI-1022
- EI-1034
- EI-1040
- EI-1050
- IDCA-10
- LJTick-CurrentShunt
- LJTick-DAC
- LJTick-DAC Testing Utility
- LJTick-DigitalOut5V
- LJTick-Divider
- LJTick-InAmp
- LJTick-InBuff
- LJTick-LVDigitalIO
- LJTick-OutBuff
- LJTick-Proto
- LJTick-RelayDriver
- LJTick-Resistance
- LJTick-VRef
- Mux80 AIN Expansion Board
- PS12DC
- RB12
- RB16
- T-Series Datasheet
- Preface: Warranty, Liability, Compliance
- 1.0 Device Overview
- 2.0 Installation
- 3.0 Communication
- 4.0 Hardware Overview
- 5.0 USB
- 6.0 Ethernet
- 7.0 WiFi (T7-Pro only)
- 8.0 LEDs
- 9.0 VS, Power Supply
- 10.0 SGND and GND
- 11.0 SPC
- 12.0 200uA and 10uA (T7 Only)
- 13.0 Digital I/O
- 13.1 Flexible I/O (T4 Only)
- 13.2 DIO Extended Features
- 13.2.1 EF Clock Source
- 13.2.2 PWM Out
- 13.2.3 PWM Out with Phase
- 13.2.4 Pulse Out
- 13.2.5 Frequency In
- 13.2.6 Pulse Width In
- 13.2.7 Line-to-Line In
- 13.2.8 High-Speed Counter
- 13.2.9 Interrupt Counter
- 13.2.10 Interrupt Counter with Debounce
- 13.2.11 Quadrature In
- 13.2.12 Interrupt Frequency In
- 13.2.13 Conditional Reset
- 13.3 I2C
- 13.4 SPI
- 13.5 SBUS
- 13.6 1-Wire
- 13.7 Asynchronous Serial
- 14.0 Analog Inputs
- 15.0 DAC
- 16.0 DB37 (T7 Only)
- 17.0 DB15
- 18.0 Internal Temp Sensor
- 19.0 RTC (T7 Only)
- 20.0 Internal Flash
- 21.0 SD Card (T7 Only)
- 22.0 OEM Versions
- 23.0 Watchdog
- 24.0 IO Config, _DEFAULT
- 25.0 Lua Scripting
- Appendix A - Specifications
- Appendix B - Drawings and CAD Models
- Appendix C - Firmware Revision History
- Appendix D - Packaging Information
- Appendix E - Software Options
- U3 Datasheet
- Preface
- 1 - Installation
- 2 - Hardware Description
- 2.1 - USB
- 2.2 - Status LED
- 2.3 - GND and SGND
- 2.4 - VS
- 2.5 - Flexible I/O (FIO/EIO)
- 2.6 - AIN
- 2.6.1 - Channel Numbers
- 2.6.2 - Converting Binary Readings to Voltages
- 2.6.3 - Typical Analog Input Connections
- 2.6.3.1 - Signal from the LabJack
- 2.6.3.2 - Unpowered Isolated Signal
- 2.6.3.3 - Signal Powered By the LabJack
- 2.6.3.4 - Signal Powered Externally
- 2.6.3.5 - Amplifying Small Signal Voltages
- 2.6.3.6 - Signal Voltages Beyond 0-2.44 Volts (and Resistance Measurement)
- 2.6.3.7 - Measuring Current (Including 4-20 mA) with a Resistive Shunt
- 2.6.3.8 - Floating/Unconnected Inputs
- 2.6.3.9 - Signal Voltages Near Ground
- 2.6.4 - Internal Temperature Sensor
- 2.7 - DAC
- 2.8 - Digital I/O
- 2.9 - Timers/Counters
- 2.9.1 - Timer Mode Descriptions
- 2.9.1.1 - PWM Output (16-Bit, Mode 0)
- 2.9.1.2 - PWM Output (8-Bit, Mode 1)
- 2.9.1.3 - Period Measurement (32-Bit, Modes 2 & 3)
- 2.9.1.4 - Duty Cycle Measurement (Mode 4)
- 2.9.1.5 - Firmware Counter Input (Mode 5)
- 2.9.1.6 - Firmware Counter Input With Debounce (Mode 6)
- 2.9.1.7 - Frequency Output (Mode 7)
- 2.9.1.8 - Quadrature Input (Mode 8)
- 2.9.1.9 - Timer Stop Input (Mode 9)
- 2.9.1.10 - System Timer Low/High Read (Modes 10 & 11)
- 2.9.1.11 - Period Measurement (16-Bit, Modes 12 & 13)
- 2.9.1.12 - Line-to-Line Measurement (Mode 14)
- 2.9.2 - Timer Operation/Performance Notes
- 2.9.1 - Timer Mode Descriptions
- 2.10 - SPC (… and SCL/SDA/SCA)
- 2.11 - DB15
- 2.12 - U3-OEM
- 2.13 - Hardware Revision Notes
- 3 - Operation
- 4 - LabJackUD High-Level Driver
- 4.1 - Overview
- 4.2 - Function Reference
- 4.2.1 - ListAll()
- 4.2.2 - OpenLabJack()
- 4.2.3 - eGet() and ePut()
- 4.2.4 - eAddGoGet()
- 4.2.5 - AddRequest()
- 4.2.6 - Go()
- 4.2.7 - GoOne()
- 4.2.8 - GetResult()
- 4.2.9 - GetFirstResult() and GetNextResult()
- 4.2.10 - DoubleToStringAddress()
- 4.2.11 - StringToDoubleAddress()
- 4.2.12 - StringToConstant()
- 4.2.13 - ErrorToString()
- 4.2.14 - GetDriverVersion()
- 4.2.15 - TCVoltsToTemp()
- 4.2.16 - ResetLabJack()
- 4.2.17 - eAIN()
- 4.2.18 - eDAC()
- 4.2.19 - eDI()
- 4.2.20 - eDO()
- 4.2.21 - eTCConfig()
- 4.2.22 - eTCValues()
- 4.3 - Example Pseudocode
- 4.3.1 - Open
- 4.3.2 - Configuration
- 4.3.3 - Analog Inputs
- 4.3.4 - Analog Outputs
- 4.3.5 - Digital I/O
- 4.3.6 - Timers & Counters
- 4.3.7 - Stream Mode
- 4.3.8 - Raw Output/Input
- 4.3.9 - Easy Functions
- 4.3.10 - SPI Serial Communication
- 4.3.11 - I²C Serial Communication
- 4.3.12 - Asynchronous Serial Communication
- 4.3.13 - Watchdog Timer
- 4.3.14 - Miscellaneous
- 4.4 - Errorcodes
- 5 - Low-level Function Reference
- 5.1 - General Protocol
- 5.2 - Low-Level Functions
- 5.2.1 - Bad Checksum
- 5.2.2 - ConfigU3
- 5.2.3 - ConfigIO
- 5.2.4 - ConfigTimerClock
- 5.2.5 - Feedback
- 5.2.5.1 - AIN: IOType = 1
- 5.2.5.2 - WaitShort: IOType=5
- 5.2.5.3 - WaitLong: IOType=6
- 5.2.5.4 - LED: IOType=9
- 5.2.5.5 - BitStateRead: IOType=10
- 5.2.5.6 - BitStateWrite: IOType=11
- 5.2.5.7 - BitDirRead: IOType=12
- 5.2.5.8 - BitDirWrite: IOType=13
- 5.2.5.9 - PortStateRead: IOType=26
- 5.2.5.10 - PortStateWrite: IOType=27
- 5.2.5.11 - PortDirRead: IOType=28
- 5.2.5.12 - PortDirWrite: IOType=29
- 5.2.5.13 - DAC# (8-bit): IOType=34,35
- 5.2.5.14 - DAC# (16-bit): IOType=38,39
- 5.2.5.15 - Timer#: IOType=42,44
- 5.2.5.16 - Timer#Config: IOType=43,45
- 5.2.5.17 - Counter#: IOType=54,55
- 5.2.5.18 - Buzzer: IOType=63
- 5.2.6 - ReadMem (ReadCal)
- 5.2.7 - WriteMem (WriteCal)
- 5.2.8 - EraseMem (EraseCal)
- 5.2.9 - Reset
- 5.2.10 - StreamConfig
- 5.2.11 - StreamStart
- 5.2.12 - StreamData
- 5.2.13 - StreamStop
- 5.2.14 - Watchdog
- 5.2.15 - SPI
- 5.2.16 - AsynchConfig
- 5.2.17 - AsynchTX
- 5.2.18 - AsynchRX
- 5.2.19 - I²C
- 5.2.20 - SHT1X
- 5.2.21 - SetDefaults (SetToFactoryDefaults)
- 5.2.22 - ReadDefaults (ReadCurrent)
- 5.2.23 - 1-Wire
- 5.3 - Errorcodes
- 5.4 - Calibration Constants
- Appendix A - Specifications
- Appendix B - Enclosure and PCB Drawings
- U3 Firmware Revision History
- U6 Datasheet
- Preface: Warranty, Liability, Compliance
- 1 - Installation
- 2 - Hardware Description
- 2.1 - USB
- 2.2 - Power and Status LED
- 2.3 - GND and SGND
- 2.4 - VS
- 2.5 - 10UA and 200UA
- 2.6 - AIN
- 2.6.1 - Channel Numbers
- 2.6.2 - Converting Binary Readings to Voltages
- 2.6.3 - Typical Analog Input Connections
- 2.6.3.1 - Signal from the LabJack
- 2.6.3.2 - Unpowered Isolated Signal
- 2.6.3.3 - Signal Powered By the LabJack
- 2.6.3.4 - Signal Powered Externally
- 2.6.3.5 - Amplifying Small Signal Voltages
- 2.6.3.6 - Signal Voltages Beyond ±10 Volts (and Resistance Measurement)
- 2.6.3.7 - Measuring Current (Including 4-20 mA) with a Resistive Shunt
- 2.6.3.8 - Floating/Unconnected Inputs
- 2.6.4 - Internal Temperature Sensor
- 2.6.5 - Signal Range
- 2.7 - DAC
- 2.8 - Digital I/O
- 2.9 - Timers/Counters
- 2.9.1 - Timer Mode Descriptions
- 2.9.1.1 - PWM Output (16-Bit, Mode 0)
- 2.9.1.2 - PWM Output (8-Bit, Mode 1)
- 2.9.1.3 - Period Measurement (32-Bit, Modes 2 & 3)
- 2.9.1.4 - Duty Cycle Measurement (Mode 4)
- 2.9.1.5 - Firmware Counter Input (Mode 5)
- 2.9.1.6 - Firmware Counter Input With Debounce (Mode 6)
- 2.9.1.7 - Frequency Output (Mode 7)
- 2.9.1.8 - Quadrature Input (Mode 8)
- 2.9.1.9 - Timer Stop Input (Mode 9)
- 2.9.1.10 - System Timer Low/High Read (Modes 10 & 11)
- 2.9.1.11 - Period Measurement (16-Bit, Modes 12 & 13)
- 2.9.1.12 - Line-to-Line Measurement (Mode 14)
- 2.9.2 - Timer Operation/Performance Notes
- 2.9.1 - Timer Mode Descriptions
- 2.10 - SPC (or VSPC)
- 2.11 - DB37
- 2.12 - DB15
- 2.13 - OEM Connector Options
- 3 - Operation
- 4 - LabJackUD High-Level Driver
- 4.1 - Overview
- 4.2 - Function Reference
- 4.2.1 - ListAll()
- 4.2.2 - OpenLabJack()
- 4.2.3 - eGet() and ePut()
- 4.2.4 - eAddGoGet()
- 4.2.5 - AddRequest()
- 4.2.6 - Go()
- 4.2.7 - GoOne()
- 4.2.8 - GetResult()
- 4.2.9 - GetFirstResult() and GetNextResult()
- 4.2.10 - DoubleToStringAddress()
- 4.2.11 - StringToDoubleAddress()
- 4.2.12 - StringToConstant()
- 4.2.13 - ErrorToString()
- 4.2.14 - GetDriverVersion()
- 4.2.15 - TCVoltsToTemp()
- 4.2.16 - ResetLabJack()
- 4.2.17 - eAIN()
- 4.2.18 - eDAC()
- 4.2.19 - eDI()
- 4.2.20 - eDO()
- 4.2.21 - eTCConfig()
- 4.2.22 - eTCValues()
- 4.3 - Example Pseudocode
- 4.3.1 - Open
- 4.3.2 - Configuration
- 4.3.3 - Analog Inputs
- 4.3.4 - Analog Outputs
- 4.3.5 - Digital I/O
- 4.3.6 - Timers & Counters
- 4.3.7 - Stream Mode
- 4.3.8 - Raw Output/Input
- 4.3.9 - Easy Functions
- 4.3.10 - SPI Serial Communication
- 4.3.11 - I²C Serial Communication
- 4.3.12 - Asynchronous Serial Communication
- 4.3.13 - Watchdog Timer
- 4.3.14 - Miscellaneous
- 4.4 - Errorcodes
- 5 - Low-level Function Reference
- 5.1 - General Protocol
- 5.2 - Low-Level Functions
- 5.2.1 - Bad Checksum
- 5.2.2 - ConfigU6
- 5.2.3 - ConfigIO
- 5.2.4 - ConfigTimerClock
- 5.2.5 - Feedback
- 5.2.5.1 - AIN: IOType = 1
- 5.2.5.2 - AIN24: IOType = 2
- 5.2.5.3 - AIN24AR: IOType = 3
- 5.2.5.4 - WaitShort: IOType=5
- 5.2.5.5 - WaitLong: IOType=6
- 5.2.5.6 - LED: IOType=9
- 5.2.5.7 - BitStateRead: IOType=10
- 5.2.5.8 - BitStateWrite: IOType=11
- 5.2.5.9 - BitDirRead: IOType=12
- 5.2.5.10 - BitDirWrite: IOType=13
- 5.2.5.11 - PortStateRead: IOType=26
- 5.2.5.12 - PortStateWrite: IOType=27
- 5.2.5.13 - PortDirRead: IOType=28
- 5.2.5.14 - PortDirWrite: IOType=29
- 5.2.5.15 - DAC# (8-bit): IOType=34,25
- 5.2.5.16 - DAC# (16-bit): IOType=38,39
- 5.2.5.17 - Timer#: IOType=42,44,46,48
- 5.2.5.18 - Timer#Config: IOType = 43, 45, 47, 49
- 5.2.5.19 - Counter#: IOType = 54, 55
- 5.2.6 - ReadMem (ReadCal)
- 5.2.7 - WriteMem (WriteCal)
- 5.2.8 - EraseMem (EraseCal)
- 5.2.9 - SetDefaults (SetToFactoryDefaults)
- 5.2.10 - ReadDefaults (ReadCurrent)
- 5.2.11 - Reset
- 5.2.12 - StreamConfig
- 5.2.13 - StreamStart
- 5.2.14 - StreamData
- 5.2.15 - StreamStop
- 5.2.16 - Watchdog
- 5.2.17 - SPI
- 5.2.18 - AsynchConfig
- 5.2.19 - AsynchTX
- 5.2.20 - AsynchRX
- 5.2.21 - I²C
- 5.2.22 - SHT1X
- 5.2.23 - 1-Wire
- 5.2.24 - StreamAddChannels
- 5.3 - Errorcodes
- 5.4 - Calibration Constants
- Appendix A - Specifications
- Appendix B - Noise and Resolution Tables
- Appendix C - Enclosure and PCB Drawings
- U6 Firmware Revision History
- Digit Datasheet (Discontinued)
- UE9 Datasheet
- Preface
- 1 - Installation
- 2 - Hardware Description
- 2.1 - USB
- 2.2 - Ethernet
- 2.3 - Vext (Screw Terminals and Power Jack)
- 2.4 - Comm and Control LEDs
- 2.5 - GND and SGND
- 2.6 - VS
- 2.7 - AIN
- 2.7.1 - Channel Numbers
- 2.7.2 - Converting Binary Readings to Voltages
- 2.7.3 - Typical Analog Input Connections
- 2.7.3.1 - Signal from the LabJack
- 2.7.3.2 - Unpowered Isolated Signal
- 2.7.3.3 - Signal Powered by the LabJack
- 2.7.3.4 - Signal Powered Externally
- 2.7.3.5 - Amplifying Small Signal Voltages
- 2.7.3.6 - Signal Voltages Beyond ±5 Volts (and Resistance Measurement)
- 2.7.3.7 - Measuring Current (Including 4-20 mA) with a Resistive Shunt
- 2.7.3.8 - Floating/Unconnected Inputs
- 2.7.4 - Internal Temperature Sensor
- 2.8 - DAC
- 2.9 - Digital I/O
- 2.10 - Timers/Counters
- 2.10.1 - Timer Mode Descriptions
- 2.10.1.1 - PWM Output (16-Bit, Mode 0)
- 2.10.1.2 - PWM Output (8-Bit, Mode 1)
- 2.10.1.3 - Period Measurement (32-Bit, Modes 2 & 3)
- 2.10.1.4 - Duty Cycle Measurement (Mode 4)
- 2.10.1.5 - Firmware Counter Input (Mode 5)
- 2.10.1.6 - Firmware Counter Input With Debounce (Mode 6)
- 2.10.1.7 - Frequency Output (Mode 7)
- 2.10.1.8 - Quadrature Input (Mode 8)
- 2.10.1.9 - Timer Stop Input (Mode 9)
- 2.10.1.10 - System Timer Low/High Read (Modes 10 & 11)
- 2.10.1.11 - Period Measurement (16-Bit, Modes 12 & 13)
- 2.10.2 - Timer Operation/Performance Notes
- 2.10.1 - Timer Mode Descriptions
- 2.11 - SCL and SDA (or SCA)
- 2.12 - DB37
- 2.13 - DB15
- 2.14 - OEM Connector Options
- 3 - Operation
- 4 - LabJackUD High-Level Driver
- 4.1 - Overview
- 4.2 - Function Reference
- 4.2.1 - ListAll()
- 4.2.2 - OpenLabJack()
- 4.2.3 - eGet() and ePut()
- 4.2.4 - eAddGoGet()
- 4.2.5 - AddRequest()
- 4.2.6 - Go()
- 4.2.7 - GoOne()
- 4.2.8 - GetResult()
- 4.2.9 - GetFirstResult() and GetNextResult()
- 4.2.10 - DoubleToStringAddress()
- 4.2.11 - StringToDoubleAddress()
- 4.2.12 - StringToConstant()
- 4.2.13 - ErrorToString()
- 4.2.14 - GetDriverVersion()
- 4.2.15 - TCVoltsToTemp()
- 4.2.16 - ResetLabJack()
- 4.2.17 - eAIN()
- 4.2.18 - eDAC()
- 4.2.19 - eDI()
- 4.2.20 - eDO()
- 4.2.21 - eTCConfig()
- 4.2.22 - eTCValues()
- 4.3 - Example Pseudocode
- 4.3.1 - Open
- 4.3.2 - Configuration
- 4.3.3 - Analog Inputs
- 4.3.4 - Analog Outputs
- 4.3.5 - Digital I/O
- 4.3.6 - Timers & Counters
- 4.3.7 - Stream Mode
- 4.3.8 - Raw Output/Input
- 4.3.9 - Easy Functions
- 4.3.10 - SPI Serial Communication
- 4.3.11 - I²C Serial Communication
- 4.3.12 - Asynchronous Serial Communication
- 4.3.13 - Watchdog Timer
- 4.3.14 - Miscellaneous
- 4.4 - Errorcodes
- 5 - Low-level Function Reference
- 5.1 - General Protocol
- 5.2 - Comm Functions
- 5.3 - Control Functions
- 5.3.1 - BadChecksum
- 5.3.2 - ControlConfig
- 5.3.3 - Feedback (and FeedbackAlt)
- 5.3.4 - SingleIO
- 5.3.5 - TimerCounter
- 5.3.6 - StreamConfig
- 5.3.7 - StreamStart
- 5.3.8 - StreamData
- 5.3.9 - StreamStop
- 5.3.10 - ReadMem
- 5.3.11 - WriteMem
- 5.3.12 - EraseMem
- 5.3.13.1 - WatchdogConfig
- 5.3.13.2 - WatchdogRead
- 5.3.13.3 - Extended WatchdogConfig
- 5.3.13.4 - WatchdogClear
- 5.3.15 - Reset
- 5.3.16 - SPI
- 5.3.17 - AsynchConfig
- 5.3.18 - AsynchTX
- 5.3.19 - AsynchRX
- 5.3.20 - I²C
- 5.3.21 - SHT1X
- 5.3.22 - StreamDAC
- 5.3.23 - SetDefaults (SetToFactoryDefaults)
- 5.3.24 - ReadDefaults (ReadCurrent)
- 5.3.25 - 1-Wire
- 5.4 - Low-Level Errorcodes
- 5.5 - Modbus
- 5.6 - Calibration Constants
- 6 - Low-level Native Examples
- Appendix A - Specifications
- Appendix B - Noise and Resolution Tables
- Appendix C - Enclosure and PCB Drawings
- UE9 Firmware Revision History
- U12 Datasheet
- 1 - Installation
- 2 - Hardware Description
- 3 - Example Applications
- 4 - Programming Reference
- 4.1 - EAnalogIn
- 4.2 - EAnalogOut
- 4.3 - ECount
- 4.4 - EDigitalIn
- 4.5 - EDigitalOut
- 4.6 - AISample
- 4.7 - AIBurst
- 4.8 - AIStreamStart
- 4.9 - AIStreamRead
- 4.10 - AIStreamClear
- 4.11 - AOUpdate
- 4.12 - AsynchConfig
- 4.13 - Asynch
- 4.14 - BitsToVolts
- 4.15 - VoltsToBits
- 4.16 - Counter
- 4.17 - DigitalIO
- 4.18 - GetDriverVersion
- 4.19 - GetErrorString
- 4.20 - GetFirmwareVersion
- 4.21 - GetWinVersion
- 4.22 - ListAll
- 4.23 - LocalID
- 4.24 - NoThread
- 4.25 - PulseOut
- 4.26 - PulseOutStart
- 4.27 - PulseOutFinish
- 4.28 - PulseOutCalc
- 4.29 - ReEnum
- 4.30 - Reset (or ResetLJ)
- 4.31 - SHT1X
- 4.32 - SHTComm
- 4.33 - SHTCRC
- 4.34 - Synch
- 4.35 - Watchdog
- 4.36 - ReadMem
- 4.37 - WriteMem
- 4.38 - BuildOptionBits (ActiveX only)
- 4.39 - FourPack (ActiveX only)
- 4.40 - Description of Errorcodes
- 5 - Low-Level Function Reference
- Appendix A - Specifications
- Appendix B - Dimensions
- Appendix C - U12 Hardware Troubleshooting
- Appendix D - Maximum Data Rates for the LabJack U12
- Accessories
4 comments
I want to understand, why a
I want to understand, why a short to ground is not a good practice to follow. I was experiencing a ac component when I measured voltage between LabJack ground and earth with the mains.
The text in this section says
The text in this section says "... a short to GND is usually not a good test for noise and accuracy." The simple answer as to why, is that because on some U3s the minimum voltage on a low-voltage analog input is greater than 0.0, thus 0.0 might not be in the valid measurement range.
In terms of AC, say you connected a 100 Hz signal that varies from -100mV to +100mV (peak-to-peak). If the minimum voltage of a low-voltage analog input on your particular U3 is +10mV, you would see the signal vary from +10mV to +100mV. The time that the signal spends from -100mV to +10mV would simply look like a flat line at +10mV.
What you describe sounds different. Are you saying you did some sort of measurement (oscilloscope?) of U3 GND versus some earth ground and saw an AC signal? It is certainly normal to see small voltages at different physical locations of even the same ground.
I am using a u3-HV for a
I am using a u3-HV for a 0-10v analog input signal on AIN3 and am getting a reading of around 1.3xxV from the labjack when the input is actually at 0V. Am I doing something wrong? Thanks
The high-voltage analog
The high-voltage analog inputs on the U3-HV sit near 1.4V when floating (Section 2.6.3.8). If your signal is trying to drive to 0.0, but only pulling the analog input down to 1.3V, that suggests that your signal is very weak (high source impedance). For comparison, jumper the analog input to GND. For more detail I suggest you start a topic on our forum and provide a link with detail about your signal/sensor.