The HardAccess property determines whether the kernel-mode driver should use "hard" or "soft" access to the I/O ports. If set to True "hard" access is employed; if set to False "soft" access is employed.
"Soft" access provides higher performance access to ports, but may fail if the port(s) addressed are already in use by another driver or you are logged not as a "root". While a little slower, "Hard" access provides more reliable access to ports.