/// <summary>
/// Lock the underlying driver.
///
/// If the underlying driver requires a "key" (such as VISA's viLock()), use the
/// value returned by LockSession() of the first session locked. If this is the
/// first call to LockSession for this shared session, the value is the suggested
/// value for the key (but the implementation may ignore this and return a
/// different value).
/// </summary>
/// <param name="exclusive">true (VI_EXCLUSIVE_LOCK), false (VI_SHARED_LOCK)</param>
/// <param name="timeout">timeout in ms ... not all drivers/sessions use this</param>
/// <param name="key">"authorization" to lock this visa session.</param>
/// <returns>authorization for other calls to LockSession of a shared session</returns>
public string LockSession(bool exclusive, int timeout, string key)
{
// If not open, report an error...
if (mSession == 0)
{
throw new IOException("Cannot lock a closed VisaSession.");
}
const int VI_ERROR_TMO = -1073807339; // = 0xBFFF0015
const int VI_ERROR_RSRC_LOCKED = -1073807345; // = 0xBFFF000F
StringBuilder buffer = new StringBuilder(256);
int error = AgVisa32.viLock(mSession,
(exclusive) ? AgVisa32.VI_EXCLUSIVE_LOCK : AgVisa32.VI_SHARED_LOCK,
timeout,
key,
buffer);
if (error < 0)
{
// If someone else has this locked, we get a timeout ... "translate"
// that error into "resource locked"
if (error == VI_ERROR_TMO)
{
error = VI_ERROR_RSRC_LOCKED;
}
AgVisa32Exception.Throw(error);
}
IsSessionLocked = true;
return(buffer.ToString());
}
