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OpenS [LJM User's Guide]

Opens a desired LabJack and associates a device handle number (connection ID).  The device handle may then be passed as an input to other functions.


const char * DeviceType,
const char * ConnectionType,
const char * Identifier,
int * Handle)


DeviceType [in]

A string containing the type of the device to be connected:

"ANY" - Open any supported LabJack device type

"T4" - Open a T4 device

"T7" - Open a T7 device

"T8" - Open a T8 device

"TSERIES" - Open any T-series device

"DIGIT" - Open a Digit-series device

For other LabJack devices, see What driver/library should I use with my LabJack?

ConnectionType [in]

A string containing the type of connection desired (USB or TCP): "ANY", "USB", "TCP", "ETHERNET", or "WIFI"

Additional UDP options:
Also "ANY_UDP" is available in LJM 1.2100 and later.

Additional TCP or UDP options:

Identifier [in]

A string that may identify the device to be connected.  To open any device, use LJM_idANY (or the string "ANY").  To specify an identifier, use a serial number, IP address, or device name. See Identifier Parameter for more information. If you don't have a device available, you can use LJM_DEMO_MODE (or the string "-2") to open a fake device.

Handle [out]

The new handle that represents the device connection.


LJM errorcode or 0 for no error.

Relevant Functions

LJM_OpenS and LJM_Open are essentially the same, except that LJM_Open uses integer parameters for DeviceType and ConnectionType rather than string  parameters.

See LJM_GetHandleInfo to retrieve information about a handle.

See LJM_ListAll or LJM_ListAllS to find multiple devices.


See the notes in Opening and Closing.

When the ConnectionType parameter of this function is network-based, this function will check the IP addresses listed in LJM_SPECIAL_ADDRESSES_FILE.


Opening a T7 via TCP using LJM_OpenS

int LJMError;
int handle;
LJMError = LJM_OpenS("T7", "TCP", "ANY", &handle);


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