[Private200]

Basically, it's going to be something like this:

pawn Код:

public OnPlayerSpawn(playerid)
{
     SetTimerEx("Savedata", 180000, true, "i", playerid);
     return 1;
}

forward Savedata(playerid);

public Savedata(playerid)
{
     SavePlayerData(playerid);
     return 1;
}

I think this shall work fine.

EDIT: If you're having any problem please post below.