diff --git a/apps/modbus/src/modbus_service.erl b/apps/modbus/src/modbus_service.erl
index da3c1a6..c8fd2e5 100644
--- a/apps/modbus/src/modbus_service.erl
+++ b/apps/modbus/src/modbus_service.erl
@@ -42,13 +42,8 @@
     %% 连接模式
     mode :: #rtu_mode{} | #tcp_mode{} | undefined,
 
-    is_pending = true :: boolean(),
-
-    socket :: gen_tcp:socket() | undefined,
-
     %% #{slaveId => DevicePid}
     devices_map = #{},
-
     %% 所有的处理过程
     processor_pids = [],
     %% alarms
@@ -100,11 +95,11 @@ init([AST = #ast{modbus = Modbus = #modbus{transport = Transport, error_log = Er
                 {rtu, Port, DelayMs} ->
 
                     {ok, ?CONNECTED, #state{ast = AST, access_log_pid = create_log_file(AccessLog), error_log_pid = create_log_file(ErrorLog),
-                        mode = #rtu_mode{port = Port, delay_ms = DelayMs}, is_pending = false,
+                        mode = #rtu_mode{port = Port, delay_ms = DelayMs},
                         queue = queue:new(), packet_id = 1, devices_map = DevicesMap, alarm_pids = []}};
                 Socket ->
                     {ok, ?CONNECTED, #state{ast = AST, access_log_pid = create_log_file(AccessLog), error_log_pid = create_log_file(ErrorLog),
-                        mode = #tcp_mode{socket = Socket}, is_pending = false,
+                        mode = #tcp_mode{socket = Socket},
                         queue = queue:new(), packet_id = 1, devices_map = DevicesMap, alarm_pids = []}}
             end;
         {error, Reason} ->
@@ -127,18 +122,12 @@ callback_mode() ->
 %% process message, this function is called.
 
 %% 请求的时候必须先加入队列，modbus需要控制请求的频率
-handle_event(info, {request, ReceiverPid, Ref, SlaveId, Address}, StateName, State = #state{mode = rtu, is_pending = IsPending, packet_id = PacketId, queue = Q}) ->
+handle_event(info, {request, ReceiverPid, Ref, SlaveId, Address}, StateName, State = #state{mode = #rtu_mode{}, packet_id = PacketId, queue = Q}) ->
     case StateName of
         ?CONNECTED ->
-            Actions = case IsPending of
-                          true ->
-                              [{next_event, info, read_next}];
-                          false ->
-                              []
-                      end,
             %% 基于队列处理, modbus不是全双工的模式
             NQ = queue:in({PacketId, ReceiverPid, Ref, SlaveId, Address}, Q),
-            {keep_state, State#state{queue = NQ, packet_id = PacketId + 1}, Actions};
+            {keep_state, State#state{queue = NQ, packet_id = PacketId + 1}, [{next_event, info, read_next}]};
         _ ->
             {keep_state, State}
     end;
@@ -153,9 +142,9 @@ handle_event(info, read_next, ?CONNECTED, State = #state{mode = #rtu_mode{port =
             Port !  {self(), {command, ReadCmd}},
             {keep_state, State#state{queue = Q2, inflight = maps:put(PacketId, {ReceiverPid, Ref}, Inflight)}};
         {empty, Q1} ->
-            {keep_state, State#state{queue = Q1, is_pending = true}}
+            {keep_state, State#state{queue = Q1}}
     end;
-handle_event(info, read_next, ?DISCONNECTED, State = #state{mode = rtu}) ->
+handle_event(info, read_next, ?DISCONNECTED, State = #state{mode = #rtu_mode{}}) ->
     {keep_state, State};
 
 %% 从port读取数据, todo 获取到的数据表示为32位整数
@@ -184,25 +173,25 @@ handle_event(info, {broadcast, Key, Val}, ?CONNECTED, State = #state{alarm_pids
 handle_event(info, {Port, {exit_status, Code}}, ?CONNECTED, State = #state{mode = #rtu_mode{port = Port}}) ->
     lager:debug("[modbus_service] port: ~p, exit with code: ~p", [Port, Code]),
     retry_connect(),
-    {next_state, ?DISCONNECTED, State#state{mode = undefined, is_pending = true}};
+    {next_state, ?DISCONNECTED, State#state{mode = undefined}};
 
 %% 处理port的退出消息
 handle_event(info, {'EXIT', Port, Reason}, ?CONNECTED, State = #state{mode = #rtu_mode{port = Port}}) ->
     lager:debug("[modbus_service] port: ~p, exit with code: ~p", [Port, Reason]),
     retry_connect(),
-    {next_state, ?DISCONNECTED, State#state{mode = undefined, is_pending = true}};
+    {next_state, ?DISCONNECTED, State#state{mode = undefined}};
 
 %% tcp退出
-handle_event(info, {tcp_closed, Socket}, ?CONNECTED, State = #state{mode = tcp, socket = Socket}) ->
+handle_event(info, {tcp_closed, Socket}, ?CONNECTED, State = #state{mode = #tcp_mode{socket = Socket}}) ->
     lager:debug("[modbus_service] socket: ~p, exit with tcp_closed", [Socket]),
     retry_connect(),
-    {next_state, ?DISCONNECTED, State#state{socket = undefined}};
+    {next_state, ?DISCONNECTED, State#state{mode = undefined}};
 
 %% 处理tcp的退出消息
-handle_event(info, {tcp_error, Socket, Reason}, ?CONNECTED, State = #state{mode = tcp, socket = Socket}) ->
+handle_event(info, {tcp_error, Socket, Reason}, ?CONNECTED, State = #state{mode = #tcp_mode{socket = Socket}}) ->
     lager:debug("[modbus_service] socket: ~p, exit with code: ~p", [Socket, Reason]),
     retry_connect(),
-    {next_state, ?DISCONNECTED, State#state{socket = undefined}};
+    {next_state, ?DISCONNECTED, State#state{mode = undefined}};
 
 %% 建立连接, todo is_pending的状态要形成闭环
 handle_event(info, {timeout, _Ref, modbus_connect}, ?DISCONNECTED, State = #state{ast = #ast{modbus = #modbus{transport = Transport}}, queue = Q}) ->
@@ -216,7 +205,7 @@ handle_event(info, {timeout, _Ref, modbus_connect}, ?DISCONNECTED, State = #stat
                       end,
             case ConnectResult of
                 {rtu, Port, DelayMs} ->
-                    {next_state, ?CONNECTED, State#state{mode = #rtu_mode{port = Port, delay_ms = DelayMs}, is_pending = false}, Actions};
+                    {next_state, ?CONNECTED, State#state{mode = #rtu_mode{port = Port, delay_ms = DelayMs}}, Actions};
                 Socket ->
                     {next_state, ?CONNECTED, State#state{mode = #tcp_mode{socket = Socket}}, Actions}
             end;