Hi Jine,
It is possible in different ways.
You can specify the connection limit in NAT stmt & STATIC natting as well. Otherwise you can use the set connection command also.
Eg: static(inside, outside) x.x.x.x 192.168.1.1 netmask 255.255.255.255 2000 500
( here we limited max connection to inside host 192.168.1.1 to 2000 from outside)
Regards
Jithesh