Can access Postgres db from Java but can't from PHP

Question

I just created a sample Postgres db on one of my computers and configured the pg_hba.conf file and postgresql.conf file to allow remote connections.

I wrote a simple java app that uses the postgre jdbc driver and could connect to the database from another machine. But when I try to run a select query using PHP, it says connection refused.

So far the PHP looks like

<?php
   $host        = "host=i have the host address here";
   $port        = "port=5432";
   $dbname      = "dbname=db here";
   $credentials = "user=username here password=password here";

   $db = pg_connect( "$host $port $dbname $credentials"  );
   if(!$db){
      echo "Error : Unable to open database\n";
   } else {
      echo "Opened database successfully\n";
   }
?>

And i get the message Warning: pg_connect(): Unable to connect to PostgreSQL server: could not connect to server: Connection refused Is the server running on host "host address here" and accepting TCP/IP connections on port 5432? Error : Unable to open database

I have all the credentials, i.e. host address, username, password correct as I can query the db from a java program.

Is there anything im doing wrong?