2.5.2 IUFOPN

1.
Function
Returns the minimum number of  I/O device that exists and is not connected (therefore can be used).
2.
Call
IUFOPN()
3.
Explanation of Parameters
IUFOPN (I) Integer value that returns a device number.
4.
Notes
(a)
This value inquires the condition of the I/O device corresponding to the device numbers 1 to 99, in ascending order, and returns the device number for the first I/O device which exists and is not connected (not open). If no I/O devices is available, it will return 0.