diff --git a/libraries/io/i2c/tb/vhdl/dev_pmbus.vhd b/libraries/io/i2c/tb/vhdl/dev_pmbus.vhd
index 15754ab7edc2c6d2a63a891110557c529c46df27..33946a4ac1cdc882e4a27b422e1bb5dbdaf0487a 100644
--- a/libraries/io/i2c/tb/vhdl/dev_pmbus.vhd
+++ b/libraries/io/i2c/tb/vhdl/dev_pmbus.vhd
@@ -32,6 +32,7 @@ ENTITY dev_pmbus IS
   PORT(
     scl         : IN    STD_LOGIC;
     sda         : INOUT STD_LOGIC;
+    vout_mode   : IN    INTEGER;
     vin         : IN    INTEGER;
     vout        : IN    INTEGER;
     iout        : IN    INTEGER;
@@ -99,6 +100,7 @@ BEGIN
   BEGIN
     IF RISING_EDGE(rd_req) THEN
       CASE cmd IS  --only model some read cmd
+        WHEN PMBUS_REG_READ_VOUT_MODE=> rd_dat <= STD_LOGIC_VECTOR(TO_SIGNED(vout_mode,8));
         WHEN PMBUS_REG_READ_VIN      => rd_dat <= STD_LOGIC_VECTOR(TO_SIGNED(vin,8));
         WHEN PMBUS_REG_READ_VOUT     => rd_dat <= STD_LOGIC_VECTOR(TO_SIGNED(vout,8));
         WHEN PMBUS_REG_READ_IOUT     => rd_dat <= STD_LOGIC_VECTOR(TO_SIGNED(iout,8));