Pico TC08 USB THERMOELEMENT DATA LOGGER PP222 Manual Do Utilizador

short usb_tc08_open_unit (void)

This routine returns a valid handle to the USB TC-08 if the driver successfully opens it. In the case of the
routine failing, see the error code explanations in the 

 section. If you wish to use

more than one USB TC-08, this routine should be called once for each unit connected to the PC the
function will return 0 if there are no more units found. The driver is thread safe and will not allow access
to a single unit from more than one application. If, therefore,  usb_tc08_open_unit does not find a
unit, check that other applications are not using the USB TC-08. This includes applications on other
user accounts on the same computer, where fast user switching is supported.

Note: The  usb_tc08_open_unit function provides a simple way to open USB TC-08 units.
However, the function call locks up the calling thread until the attached USB TC-08 unit has been fully
enumerated. If a single threaded application needs to perform concurrent processing, such as
displaying a progress bar, 

 should be used.

None

Positive short

- The handle to a unit.

0

- No more units were found.

-1

- Unit failed to open. Call 

 with a handle of 0 to obtain

the error code.

Example

The following code is a fragment of a C application which demonstrates how to open multiple units with
the USB TC-08 driver. The handles to the open units are stored in an array for later use:

//======================================================

// Opening multiple units

//======================================================

for

 (i = 

0

()) > 

0

; i++)

 {

// store the handle in an array

 handle_array[i] = new_handle;

 }

no_of_units = i;

// deal with the error if there is one,

// if new_handle was zero, then there was no error

// and we reached the last available unit

if

 (new_handle == -

1

)

 {

(

0

);

 printf(

"Unit failed to open\nThe error code is %d"

, error_code);