Check value instead of UDF field

NON-APPROVED/COMMON/DEVICES/vacuum/vvs/Faceplate/vac_vvs-interlock_device.bob

@@ -12,11 +12,10 @@
     <vertical_alignment>1</vertical_alignment>
     <rules>
       <rule name="Text" prop_id="text" out_exp="true">
-        <exp bool_exp="pvInt1 == 0">
+        <exp bool_exp="pvStr0 != ''">
           <expression>pvStr0 + ':'</expression>
         </exp>
         <pv_name>$(ITLck):Device</pv_name>
-        <pv_name>$(ITLck):Device.UDF</pv_name>
       </rule>
     </rules>
     <tooltip>The device driving this interlock</tooltip>