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24.0 IO Config, _DEFAULT [T-Series Datasheet]


IO_Config controls the default configuration that will be used when the device boots up, and can set an already running device to a known state. The default configuration sets the values that will be used during boot-up for digital directions, digital states, DACs, AIN_EF, and DIO_EF. IO_Config can also apply either the default or factory configuration to a device that is already running.




Registers ending with "_DEFAULT" will store non-volatile settings. These non-volatile settings will be used to configure the T-Series device during boot-up.


  • DEFAULT – A saved configuration set. These are also the settings that will be used when the device boots up.

  • FACTORY – The default settings that are loaded when the device is tested at LabJack.

  • CURRENT – The device's current settings. 

Register Listing

Use the following registers to configure IO_Config:


The IO_CONFIG_CURRENT_CRC32 register returns a CRC32 of the configuration data:

The CRC can be used to detect configuration changes. Calculating the checksum takes between 5 and 15 ms. Some configurations are excluded from the CRC because they are expected to change during normal operations. The excluded configurations are:

  • Digital States

  • Digital Directions

  • DAC Voltages

Factory Reset

IO_Config settings can be cleared by a factory reset. See the 11.0 SPC section for more information.

Startup Delay

When a T-Series device starts up it must perform an initialization sequence before the startup defaults can be applied. Before the startup settings are applied, all DIO are in the input state which has a 100k pull-up to 3.3V.  EIO0 is a special case, during this pre-config time only, where it behaves more like it has a 10k pull-up to 3.3V. The pull-ups on the T4 default to off. Without the pull-ups the lines are floating until the startup settings are applied. Startup defaults are divided into two groups depending on where they are applied in the startup sequence. The two groups are:

  • Fast DIO - Directions and States for DIO lines which are not used for SPC jumpers. Typically applied ~2.5 ms (Tested with T7 1.0288) after power is applied.  This is true for all T4 bootloaders, and T7 bootloader 0.96.  Prior to T7 bootloader 0.96, all DIO acted like "Slow DIO" described below.

  • Slow DIO - Directions and States for DIO lines which are used for SPC jumpers, DIO_EF for all lines, AIN_EF, Ethernet, analog settings, etc. Typically applied ~700 ms  (Tested with T7 1.0288) after power is applied. Note that the firmware update process will increase this time to ~12 seconds.

Saving I/O Configurations using Kipling

The Global Configurations and Power-Up Defaults tabs in Kipling can also be used to setup I/O Configurations.


Use normal current configuration registers to write some values, and then save those as defaults so they are in effect at power-up:

AIN_ALL_RANGE = 0.1 // Set current range of all AIN to +/-0.1V

AIN_ALL_RESOLUTION_INDEX = 12 // Set current resolution index of all AIN to 12.

IO_CONFIG_SET_DEFAULT_TO_CURRENT = 1 // Set power-up defaults to current values.

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