[syslog-ng] help about multiple files in syslog-ng

Hi; I want some information regarding to multiple files in syslog-ng; The scenerio is that i have 4 devices normally router and i want information of each device but with same facility (local7) and this information must be in each seperate file say router1, router2 .... so on. How i can do this; I have attached a router via console and trying to access its log but not succeeded. Plz guide me to the solution. -- Sarfraz