diff --git a/protos/device_state.proto b/protos/device_state.proto
index 6ce2530..12c73f5 100644
--- a/protos/device_state.proto
+++ b/protos/device_state.proto
@@ -161,8 +161,12 @@ message TrainState{
   common.TrainEndsState trainEndsA = 18;
   //列车B端
   common.TrainEndsState trainEndsB = 19;
+  // 列车尾端所在设备ID
+  uint32 tailDeviceId = 20;
+  // 列车尾端所在设备偏移量
+  int64 tailOffset = 21;
   // BTM状态
-  BTMState btmState = 20;
+  BTMState btmState = 22;
 }
 
 // 动力学列车状态