diff --git a/docs/commandref.html b/docs/commandref.html
index 2c2f6f030..1d0e89d4a 100644
--- a/docs/commandref.html
+++ b/docs/commandref.html
@@ -1012,13 +1012,14 @@ A line ending with \ will be concatenated with the next one, so long lines
 <a name="rereadcfg"></a>
 <h3>rereadcfg</h3>
 <ul>
-  <code>rereadcfg</code>
+  <code>rereadcfg [fhem-config-file]</code>
   <br><br>
-  Re-read the configuration file.
-  Note: The statefile will be saved first, then the config file will be read
+  Re-read the configuration file, or the optionally specified file.
+  The sequence: the statefile will be saved first, then all devices will be
+  deleted, then the original config file (or the specified file) will be read
   (all devices will be initialized again), and at last the statefile will be
-  reloaded. It triggers upon completion the global:REREADCFG event.
-  All existing connections up to the one issuing the rereadcfg will be closed.
+  reloaded. It triggers upon completion the global:REREADCFG event.  All
+  existing connections up to the one issuing the rereadcfg will be closed.
   <br><br>
   Example:
   <ul>
diff --git a/fhem.pl b/fhem.pl
index 23e9ab19e..34162a1e4 100755
--- a/fhem.pl
+++ b/fhem.pl
@@ -235,7 +235,7 @@ $modules{Global}{AttrFn} = "GlobalAttr";
   "rename"  => { Fn=>"CommandRename",
 	    Hlp=>"<old> <new>,rename a definition" },
   "rereadcfg"  => { Fn=>"CommandRereadCfg",
-	    Hlp=>",reread the config file" },
+	    Hlp=>"[configfile],read in the config after deleting everything" },
   "save"    => { Fn=>"CommandSave",
 	    Hlp=>"[configfile],write the configfile and the statefile" },
   "set"     => { Fn=>"CommandSet",
@@ -882,7 +882,10 @@ CommandRereadCfg($$)
 {
   my ($cl, $param) = @_;
   my $name = $cl->{NAME} if($cl);
+  my $cfgfile = ($param ? $param : $attr{global}{configfile});
+  return "Cannon open $cfgfile: $!" if(! -f $cfgfile);
 
+  $attr{global}{configfile} = $cfgfile;
   WriteStatefile();
 
   $reread_active=1;
@@ -896,7 +899,6 @@ CommandRereadCfg($$)
     delete $defs{$d};
   }
 
-  my $cfgfile = $attr{global}{configfile};
   %comments = ();
   %defs = ();
   %attr = ();