diff --git a/apps/modbus/src/modbus_device.erl b/apps/modbus/src/modbus_device.erl
index a290ade..4b1d42d 100644
--- a/apps/modbus/src/modbus_device.erl
+++ b/apps/modbus/src/modbus_device.erl
@@ -100,7 +100,7 @@ handle_info({timeout, _, {poll_ticker, Name}}, State = #state{parent_pid = Paren
     %% 读取采集项目
     ReceiverPid = self(),
     Ref = make_ref(),
-    ParentPid ! {request, ReceiverPid, Ref, SlaveId, Address},
+    ParentPid ! {request, ReceiverPid, Ref, SlaveId, Address, 1},
 
     {noreply, State#state{inflight = maps:put(Ref, Name, Inflight)}};
 
diff --git a/apps/modbus/src/modbus_service.erl b/apps/modbus/src/modbus_service.erl
index c8fd2e5..dd3d5dd 100644
--- a/apps/modbus/src/modbus_service.erl
+++ b/apps/modbus/src/modbus_service.erl
@@ -20,8 +20,7 @@
 -export([init/1, handle_event/4, terminate/3, code_change/4, callback_mode/0]).
 
 %% rtu指令
--define(MODBUS_CONNECT, 16#01).
--define(MODBUS_READ, 16#02).
+-define(MODBUS_READ, 16#01).
 
 %% 当前的状态
 -define(DISCONNECTED, disconnected).
@@ -33,7 +32,9 @@
 
 -record(rtu_mode, {
     port :: erlang:port(),
-    delay_ms = 0 :: integer()
+    delay_ms = 0 :: integer(),
+    %% 信道是否在忙
+    is_busy = false
 }).
 
 -record(state, {
@@ -122,25 +123,27 @@ 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_mode{}, packet_id = PacketId, queue = Q}) ->
+handle_event(info, {request, ReceiverPid, Ref, SlaveId, Address, Cnt}, StateName, State = #state{mode = #rtu_mode{}, packet_id = PacketId, queue = Q}) ->
     case StateName of
         ?CONNECTED ->
             %% 基于队列处理, modbus不是全双工的模式
-            NQ = queue:in({PacketId, ReceiverPid, Ref, SlaveId, Address}, Q),
+            NQ = queue:in({PacketId, ReceiverPid, Ref, SlaveId, Address, Cnt}, Q),
             {keep_state, State#state{queue = NQ, packet_id = PacketId + 1}, [{next_event, info, read_next}]};
         _ ->
             {keep_state, State}
     end;
 
 %% rtu 模式下读取下一个任务
-handle_event(info, read_next, ?CONNECTED, State = #state{mode = #rtu_mode{port = Port}, queue = Q, inflight = Inflight}) ->
+handle_event(info, read_next, ?CONNECTED, State = #state{mode = #rtu_mode{is_busy = true}}) ->
+    {keep_state, State};
+handle_event(info, read_next, ?CONNECTED, State = #state{mode = Mode = #rtu_mode{port = Port}, queue = Q, inflight = Inflight}) ->
     lager:debug("[modbus_service] read next, q: ~p, port is: ~p", [queue:to_list(Q), Port]),
 
     case queue:out(Q) of
-        {{value, {PacketId, ReceiverPid, Ref, SlaveId, Address}}, Q2} ->
-            ReadCmd = <<?MODBUS_READ:8, PacketId:32, SlaveId:8, Address:16>>,
+        {{value, {PacketId, ReceiverPid, Ref, SlaveId, Address, Cnt}}, Q2} ->
+            ReadCmd = <<?MODBUS_READ:8, PacketId:32, SlaveId:8, Address:16, Cnt:16>>,
             Port !  {self(), {command, ReadCmd}},
-            {keep_state, State#state{queue = Q2, inflight = maps:put(PacketId, {ReceiverPid, Ref}, Inflight)}};
+            {keep_state, State#state{queue = Q2, mode = Mode#rtu_mode{is_busy = true}, inflight = maps:put(PacketId, {ReceiverPid, Ref}, Inflight)}};
         {empty, Q1} ->
             {keep_state, State#state{queue = Q1}}
     end;
@@ -148,7 +151,8 @@ 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
-handle_event(info, {Port, {data, <<?MODBUS_READ:8, PacketId:32, Val:32>>}}, ?CONNECTED, State = #state{mode = #rtu_mode{port = Port, delay_ms = DelayMs}, inflight = Inflight}) ->
+handle_event(info, {Port, {data, <<?MODBUS_READ:8, PacketId:32, Val/binary>>}}, ?CONNECTED, State = #state{mode = Mode = #rtu_mode{port = Port, delay_ms = DelayMs}, inflight = Inflight}) ->
+    lager:debug("[device_service] read port data packet_id: ~p, val: ~p", [PacketId, Val]),
     NInflight = case maps:take(PacketId, Inflight) of
                     error ->
                         Inflight;
@@ -157,11 +161,16 @@ handle_event(info, {Port, {data, <<?MODBUS_READ:8, PacketId:32, Val:32>>}}, ?CON
                         Inflight0
                 end,
     lager:debug("[modbus_service] port data is: ~p", [{PacketId, Val}]),
-    %% 读取下一条
-    erlang:start_timer(DelayMs, self(), read_next),
+
+    %% 通讯的过程需要一个空闲时间
+    erlang:start_timer(DelayMs, self(), delay_locking),
 
     {keep_state, State#state{inflight = NInflight}};
 
+%% 锁定一个空闲时间, 把状态标记为空闲
+handle_event(info, {timeout, _, delay_locking}, ?CONNECTED, State = #state{mode = Mode = #rtu_mode{}}) ->
+    {keep_state, State#state{mode = Mode#rtu_mode{is_busy = false}}, [{next_event, info, read_next}]};
+
 %% 广播消息
 handle_event(info, {broadcast, Key, Val}, ?CONNECTED, State = #state{alarm_pids = AlarmPids}) ->
     %% 推送告警信息