diff --git a/fhem/FHEM/33_readingsGroup.pm b/fhem/FHEM/33_readingsGroup.pm
index 452df19bc..b037ef8b1 100644
--- a/fhem/FHEM/33_readingsGroup.pm
+++ b/fhem/FHEM/33_readingsGroup.pm
@@ -119,6 +119,8 @@ readingsGroup_updateDevices($)
 
   $hash->{CONTENT} = \%list;
   $hash->{DEVICES} = \@devices;
+
+  $hash->{fhem}->{last_update} = gettimeofday();
 }
 
 sub readingsGroup_Define($$)
@@ -213,6 +215,13 @@ readingsGroup_2html($)
 
   return undef if( !$hash );
 
+  if( $hash->{DEF} =~ m/=/ ) {
+    if( !$hash->{fhem}->{last_timeout}
+        || gettimeofday() - $hash->{fhem}->{last_timeout} > 600 ) {
+      readingsGroup_updateDevices($hash);
+    }
+  }
+
   my $d = $hash->{NAME};
 
   my $show_heading = !AttrVal( $d, "noheading", "0" );