diff --git a/apps/counter/api/serializers.py b/apps/counter/api/serializers.py
index 2df8fbf..d3204d8 100644
--- a/apps/counter/api/serializers.py
+++ b/apps/counter/api/serializers.py
@@ -164,7 +164,7 @@ class DeviceInfoSerializer(serializers.ModelSerializer):
     def get_status(self, obj):
         return obj.online
 
-    def get_count(self, obj):
+    def get_count(self, obj) ->str:
         try:
             # self.latest = DeviceCount.objects.filter(device_id=obj.device_id).order_by('-data_time')[0]
             self.latest = get_latest(obj.device_id)
@@ -172,19 +172,19 @@ class DeviceInfoSerializer(serializers.ModelSerializer):
             self.latest = None
         if self.latest:
             return self.latest['count']
-        return 0
+        return '0'
 
-    def get_signal(self, obj):
+    def get_signal(self, obj) ->str:
         if self.latest:
             return self.latest['csq']
-        return 0
+        return '0'
 
-    def get_energy(self, obj):
+    def get_energy(self, obj) ->str:
         if self.latest:
             if float(self.latest['vol']) <= 100:
                 return '{}{}'.format(round(float(self.latest['vol']), 1), '%')
             return get_vol(obj.device_id, self.latest['vol'])
-        return 0
+        return '0%'
 
     def get_coordinate(self, obj):
         if self.cur_device: