diff --git a/fhem/FHEM/10_FS20.pm b/fhem/FHEM/10_FS20.pm
index 43d477795..dd248a89f 100755
--- a/fhem/FHEM/10_FS20.pm
+++ b/fhem/FHEM/10_FS20.pm
@@ -109,7 +109,7 @@ FS20_Initialize($)
   $hash->{DefFn}     = "FS20_Define";
   $hash->{UndefFn}   = "FS20_Undef";
   $hash->{ParseFn}   = "FS20_Parse";
-  $hash->{AttrList}  = "IODev follow-on-for-timer:1,0 do_not_notify:1,0 ignore:0,1 dummy:1,0 showtime:1,0 model;fs20hgs,fs20hgs,fs20pira,fs20piri,fs20s20,fs20s8,fs20s4,fs20s4a,fs20s4m,fs20s4u,fs20s4ub,fs20sd,fs20sn,fs20sr,fs20ss,fs20str,fs20tfk,fs20tfk,fs20tk,fs20uts,fs20ze,fs20as1,fs20as4,fs20di,fs20du,fs20ls,fs20ms2,fs20rst,fs20sa,fs20sig,fs20st,fs20sv,fs20usr loglevel:0,1,2,3,4,5,6";
+  $hash->{AttrList}  = "IODev follow-on-for-timer:1,0 do_not_notify:1,0 ignore:0,1 dummy:1,0 showtime:1,0 model;fs20hgs,fs20hgs,fs20pira,fs20piri,fs20s20,fs20s8,fs20s4,fs20s4a,fs20s4m,fs20s4u,fs20s4ub,fs20sd,fs20sn,fs20sr,fs20ss,fs20str,fs20tfk,fs20tfk,fs20tk,fs20uts,fs20ze,fs20as1,fs20as4,fs20di,fs20du,fs20ls,fs20ms2,fs20rst,fs20sa,fs20sig,fs20st,fs20sv,fs20usr exchange_on_off loglevel:0,1,2,3,4,5,6";
 
 }
 
@@ -162,6 +162,14 @@ FS20_Set($@)
   return "no set value specified" if($na < 2 || $na > 3);
   return "Readonly value $a[1]" if(defined($readonly{$a[1]}));
 
+  if($attr{$a[0]} && $attr{$a[0]}{exchange_on_off}) {
+    if($a[1] =~ m/off/) {
+      $a[1] =~ s/off/on/;
+    } else {
+      $a[1] =~ s/on/off/;
+    }
+  }
+
   my $c = $fs20_c2b{$a[1]};
   if(!defined($c)) {
 
@@ -339,7 +347,7 @@ FS20_Parse($$)
 
   my $dur = 0;
   my $cx = hex($cde);
-  if($cx & 0x20) {
+  if($cx & 0x20) {      # Timed command
     $dur = hex(substr($msg, 26, 2));
     my $i = ($dur & 0xf0) / 16;
     my $j = ($dur & 0xf);
@@ -351,6 +359,7 @@ FS20_Parse($$)
   $v = "unknown_$cde" if(!defined($v));
   $v .= " $dur" if($dur);
 
+
   my $def = $modules{FS20}{defptr}{"$dev $btn"};
   if($def) {
     my @list;
@@ -358,6 +367,14 @@ FS20_Parse($$)
       my $lh = $def->{$n};
       $n = $lh->{NAME};        # It may be renamed
 
+      if($attr{$n} && $attr{$n}{exchange_on_off}) {
+        if($v =~ m/off/) {
+          $v =~ s/off/on/;
+        } else {
+          $v =~ s/on/off/;
+        }
+      }
+
       return "" if(IsIgnored($n));   # Little strange.
 
       $lh->{CHANGED}[0] = $v;
diff --git a/fhem/docs/commandref.html b/fhem/docs/commandref.html
index de2217d5b..dace4f1b9 100644
--- a/fhem/docs/commandref.html
+++ b/fhem/docs/commandref.html
@@ -1300,7 +1300,13 @@ A line ending with \ will be concatenated with the next one, so long lines
         list command (only if it is explicitely asked for it), nor will it
         appear in commands which use some wildcard/attribute as name specifiers
         (see <a href="#devspec">devspec</a>). You still get them with the
-        "ignored=1" special devspec.  </li>
+        "ignored=1" special devspec.
+        </li><br>
+
+    <a name="exchange_on_off"></a>
+    <li>exchange_on_off<br>
+        Exchange on and off (and on-for-timer, etc). Both reception and sending
+        is exchanged.</li>
 
   </ul>
 </ul>
diff --git a/fhem/docs/fhem.html b/fhem/docs/fhem.html
index 457790f43..4025124ab 100644
--- a/fhem/docs/fhem.html
+++ b/fhem/docs/fhem.html
@@ -241,6 +241,12 @@
         <li>Linux driver installation:
           <a href="http://www.koeniglich.de/fhem/linux.html">
           http://www.koeniglich.de/fhem/linux.html</a></li>
+        <li>Misc USB problems:
+          <a href="http://www.koeniglich.de/fhem/USB.html">
+          http://www.koeniglich.de/fhem/USB.html</a></li>
+        <li>Russels Blog for Windows user:
+          <a href="http://www.eclipcecreate.co.uk/category/FHEM.aspx">
+          http://www.eclipcecreate.co.uk/category/FHEM.aspx</a> <br>
         <li>Windows driver installation:
           <a href="http://fhz4linux.info/tiki-index.php?page=Driver%20installation">
           http://fhz4linux.info/tiki-index.php?page=Driver%20installation</a> <br>