Cicode Programming Reference > Cicode Function Categories > Task Functions Introduction > SemOpen


Opens a semaphore for access control. When the semaphore is opened, it is initially signalled. Use a semaphore for controlling access to a restricted device, for example, to stop another Cicode task accessing a device while it is in use. You might require semaphores for some Cicode operations, because they can access a device that is critical. (Cicode is a multi-tasking system.)

Note: This function is process-based, not computer-based, and so will only prevent access to a critical section within a single process. This function only works between Cicode tasks within the same process.


SemOpen(Name, Mode)


The name of the semaphore.


The mode of the open:

0 - Open existing semaphore.

1 - Create new semaphore.

2 - Attempts to open an existing semaphore. If the semaphore does not exist, it will create it.

Return Value

The semaphore handle, or -1 if the semaphore was not opened successfully. The semaphore handle identifies the table where all data on the associated semaphore is stored.

Related Functions

SemClose, SemSignal, SemWait



See Also

Task Functions