diff --git a/fhem/FHEM/10_KNX.pm b/fhem/FHEM/10_KNX.pm
index d84223b44..62649ae46 100644
--- a/fhem/FHEM/10_KNX.pm
+++ b/fhem/FHEM/10_KNX.pm
@@ -22,6 +22,7 @@
 # ABU 20180605 Corrected dpt18
 # ABU 20180605 Added example for autogenerated devices
 # ABU 20180605 Added workaround for STATE
+# ABU 20180606 Fixed dpt18, fixed offset-addition in decode (was "-" instead of "+"), fixed issue with slider
 
 package main;
 
@@ -31,7 +32,7 @@ use Encode;
 use SetExtensions;
 
 #set to 1 for debug
-my $debug = 0;
+my $debug = 1;
 
 #string constant for autocreate
 my $modelErr = "MODEL_NOT_DEFINED";
@@ -199,7 +200,7 @@ my %dpttypes = (
 	"dpt17.001" 	=> {CODE=>"dpt5", UNIT=>"", FACTOR=>1, OFFSET=>0, PATTERN=>qr/[+-]?\d{1,3}/i, MIN=>0, MAX=>63},
 
 	# Scene, 1-64
-	"dpt18.001" 	=> {CODE=>"dpt5", UNIT=>"", FACTOR=>1, OFFSET=>-1, PATTERN=>qr/[+-]?\d{1,3}/i, MIN=>1, MAX=>64},
+	"dpt18.001" 	=> {CODE=>"dpt5", UNIT=>"", FACTOR=>1, OFFSET=>1, PATTERN=>qr/[+-]?\d{1,3}/i, MIN=>1, MAX=>64},
 	
 	#date and time
 	"dpt19"			=> {CODE=>"dpt19", UNIT=>"", FACTOR=>undef, OFFSET=>undef, PATTERN=>qr/(((3[01]|[0-2]?[0-9]).(1[0-2]|0?[0-9]).(19[0-9][0-9]|2[01][0-9][0-9]))_((2[0-4]|[0?1][0-9]):(60|[0?1-5]?[0-9]):(60|[0?1-5]?[0-9])))|(now)/i, MIN=>undef, MAX=>undef},
@@ -508,7 +509,9 @@ KNX_Define($$) {
 		{
 			my $min = $dptDetails->{MIN};
 			my $max = $dptDetails->{MAX};
-			$setlist = ":slider," . $min . "," . int(($max-$min)/100) . "," . $max;
+			my $interval = int(($max-$min)/100);
+			$interval = 1 if ($interval == 0);
+			$setlist = ":slider," . $min . "," . $interval . "," . $max;
 		}
 		#on/off/...
 		elsif (defined ($dptDetails->{MIN}))
@@ -1822,7 +1825,7 @@ KNX_decodeByDpt ($$$) {
 		$state = 0 - $state if (not ($numval & 8));
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);
@@ -1834,7 +1837,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);
@@ -1847,7 +1850,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);		
@@ -1859,7 +1862,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);		
@@ -1872,7 +1875,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 		
 		$state = sprintf ("%.0f", $state);		
@@ -1889,7 +1892,7 @@ KNX_decodeByDpt ($$$) {
 		$numval = (1 << $exp) * 0.01 * $mant;
 
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 		
 		$state = sprintf ("%.2f","$numval");
@@ -1924,7 +1927,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;	
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);		
@@ -1937,7 +1940,7 @@ KNX_decodeByDpt ($$$) {
 		$state = $numval;
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 
 		$state = sprintf ("%.0f", $state);		
@@ -1948,7 +1951,7 @@ KNX_decodeByDpt ($$$) {
 		$numval = unpack "f", pack "L", hex ($value);
 		
 		#correct value
-		$state -= $offset if (defined ($offset));
+		$state += $offset if (defined ($offset));
 		$state *= $factor if (defined ($factor));
 		
 		$state = sprintf ("%.3f","$numval");