diff --git a/route/api/modbus.js b/route/api/modbus.js
index 3d6de7b..b500b3a 100644
--- a/route/api/modbus.js
+++ b/route/api/modbus.js
@@ -543,6 +543,7 @@ router
         if (!('func' in arr.data) || arr.data.func.length == 0) return n('ERR0055');
         if (!('addr' in arr.data) || arr.data.addr.length == 0) return n('ERR0048');
         if (!('value' in arr.data) || arr.data.value.length == 0) return n('ERR0049');
+        if (arr.data.value > 65535) return n('ERR0049');
 
         let cmd = `mbtcpm ${arr.data.ip} ${arr.data.node} ${arr.data.func} ${arr.data.addr} ${arr.data.value}`;
         res.api_res = {