diff --git a/on_off.rb b/on_off.rb
index 032e304..9dcf8e8 100644
--- a/on_off.rb
+++ b/on_off.rb
@@ -6,7 +6,7 @@ value = ARGV[0]&.to_i
 ModBus::RTUClient.new("/dev/ttyUSB0", 9600) do |cl|
   cl.with_slave(7) do |slave|
     regs = slave.holding_registers
-    regs[16] = value
+    regs[22] = value
     sleep 0.1
   end
 end