diff --git a/protos/stationLayoutGraphics.proto b/protos/stationLayoutGraphics.proto
index b87455f..ed37b72 100644
--- a/protos/stationLayoutGraphics.proto
+++ b/protos/stationLayoutGraphics.proto
@@ -361,7 +361,7 @@ message CalculateLink {
   RelatedRef aRelatedRef = 4; // A端（最小端）关联的端点
   RelatedRef bRelatedRef = 5; // B端（最大端）关联的端点
   repeated DevicePosition devicePositions = 6; //设备在link上的位置
-
+  int32 index = 7; //link唯一标识 
   message DevicePosition {
     int32 offset = 1;
     string deviceId = 2;