diff --git a/on_off.rb b/on_off.rb
index 9395907..998757f 100644
--- a/on_off.rb
+++ b/on_off.rb
@@ -2,7 +2,7 @@ require "rmodbus"
 require "ccutrer-serialport"
 
 controller_id = ARGV[0]&.to_i
-value = ARGV[0]&.to_i
+value = ARGV[1]&.to_i
 
 ModBus::RTUClient.new("/dev/ttyUSB0", 9600) do |cl|
   cl.with_slave(controller_id) do |slave|