Configuring Mongos and Config Server


I have Config Servers Replica Set spread across multiple Data Centers and I want the Mongos to read from the secondary node which is in the same Data Center( or atleast nearest). So is it possible to configure Mongos(Router) to read from the Secondary Config Server instead of the Primary one?

Also, how frequently do Mongos talk to the Config Server, and is there any property to control the frequency?