Return Code	Significance
0	all ok
1	locking flag not changed before
-1	no graphical interface initialized

Only call this function after you have successfully (return code = 0) released the communication locking using the function dal_gfi_fre_loc.

Example:

• fre = dal_gfi_fre_loc ()
• ... interactive actions
• if (!fre) dal_gfi_res_loc ()