diff --git a/lib/ladder_drive/protocol/omron/fins_tcp_protocol.rb b/lib/ladder_drive/protocol/omron/fins_tcp_protocol.rb
index <HASH>..<HASH> 100644
--- a/lib/ladder_drive/protocol/omron/fins_tcp_protocol.rb
+++ b/lib/ladder_drive/protocol/omron/fins_tcp_protocol.rb
@@ -277,8 +277,8 @@ p e
       else
         buf[4] = destination_node
       end
-      buf[6] = source_node
-      buf[7] = source_unit
+      buf[7] = source_node
+      buf[8] = source_unit
 
       buf
     end
fix to set source node and unit