diff --git a/src/main/scala/backBoard/BackBoardMst.scala b/src/main/scala/backBoard/BackBoardMst.scala
index ca19cc4..0bbc99e 100644
--- a/src/main/scala/backBoard/BackBoardMst.scala
+++ b/src/main/scala/backBoard/BackBoardMst.scala
@@ -195,6 +195,10 @@ trait BackBoardMstFSMC{ this: BackBoardMstBase =>
 
     }
 
+    when( wrRegAddr === 2.U ){
+      slvNum := wrRegData
+    }
+
     when( wrRegAddr === 4.U ){
       testReg := wrRegData
     }