Implementation banned IP in FortiWeb

Implementation banned IP in FortiWeb

I have a FortiWeb appliance and I have the following algorithm:

IF THREAT_LEVEL == 'CRITICAL' THEN
   $STORED_BANNED_SRC_IP = $SRC_IP
   banned_IP($SRC_IP)
   AND after 30 minutes I want to unbanned $src_ip
   UNBANNDED_IP($STORED_BANNED_SRC_IP)

How can I implement it in Fortiweb?