Simulink freezes after long simulation

Hi all,

I am building a model in which I used level 2 matlab S function to create my own TCP/IP block. The model suppose to taking input value through TCP/IP protocol then feed them into a PID block to control to a pump. I am able to run the whole model, however, after 1 - 10 hours of simulation Simulink freezes so I had to use Ctrl + C to terminate the simulation and I got this error "Error evaluating registered method 'Outputs' of MATLAB S-Function 'Read_Analog_IO_1' in 'AVN_COD_control/Analog_IO_1/Level-2 MATLAB S-Function'. Program interruption (Ctrl-C) has been detected." And the time of freezing varies for each simulation.

Any suggestion to solve this problem will be highly appreciated.

Below is how my level 2 matlab S-function code look like:

      function Read_Analog_IO_1(block)
      setup(block);
      function setup(block)

      % Register number of ports
      block.NumInputPorts  = 1;
      block.NumOutputPorts = 4;

      % Setup port properties to be inherited or dynamic
      block.SetPreCompInpPortInfoToDynamic;
      block.SetPreCompOutPortInfoToDynamic;

      block.RegBlockMethod('SetInputPortSamplingMode',@SetInputPortSamplingMode);
      block.RegBlockMethod('SetInputPortDimensions', @SetInpPortDims);
      block.RegBlockMethod('Outputs', @Output);

      % Override input port properties
      block.InputPort(1).Dimensions        = 1;
      block.InputPort(1).DatatypeID  = 0;  % double
      block.InputPort(1).Complexity  = 'Real';
      block.InputPort(1).DirectFeedthrough = true;

      % Override output port properties
      block.OutputPort(1).Dimensions       = 1;
      block.OutputPort(1).DatatypeID  = 0; % double
      block.OutputPort(1).Complexity  = 'Real';
      block.OutputPort(1).SamplingMode = 'Sample';

      block.OutputPort(2).Dimensions       = 1;
      block.OutputPort(2).DatatypeID  = 0; % double
      block.OutputPort(2).Complexity  = 'Real';
      block.OutputPort(2).SamplingMode = 'Sample';

      block.OutputPort(3).Dimensions       = 1;
      block.OutputPort(3).DatatypeID  = 0; % double
      block.OutputPort(3).Complexity  = 'Real';
      block.OutputPort(3).SamplingMode = 'Sample';

      block.OutputPort(4).Dimensions       = 1;
      block.OutputPort(4).DatatypeID  = 0; % double
      block.OutputPort(4).Complexity  = 'Real';
      block.OutputPort(4).SamplingMode = 'Sample';

      % Register parameters
      block.NumDialogPrms     = 0;

      % Register sample times
      %  [0 offset]            : Continuous sample time
      %  [positive_num offset] : Discrete sample time
      %
      %  [-1, 0]               : Inherited sample time
      %  [-2, 0]               : Variable sample time
      block.SampleTimes = [1 0];

      block.SimStateCompliance = 'DefaultSimState';

      block.RegBlockMethod('PostPropagationSetup',    @DoPostPropSetup);
      block.RegBlockMethod('InitializeConditions', @InitializeConditions);
      block.RegBlockMethod('Start', @Start);
      block.RegBlockMethod('Outputs', @Outputs);     % Required
      block.RegBlockMethod('Update', @Update);
      block.RegBlockMethod('Derivatives', @Derivatives);
      block.RegBlockMethod('Terminate', @Terminate); % Required

      function SetInputPortSamplingMode(block, idx, fd)
      block.InputPort(idx).SamplingMode = fd;
      block.OutputPort(1).SamplingMode = fd;
      block.OutputPort(2).SamplingMode = fd;
      block.OutputPort(3).SamplingMode = fd;
      block.OutputPort(4).SamplingMode = fd;

       function SetInpPortDims(block, idx, di)
        block.InputPort(idx).Dimensions = di;
        block.OutputPort(1).Dimensions = di;
        block.OutputPort(2).Dimensions = di;
        block.OutputPort(3).Dimensions = di;
        block.OutputPort(4).Dimensions = di;

      function DoPostPropSetup(block)
      block.NumDworks = 1;

        block.Dwork(1).Name            = 'x1';
        block.Dwork(1).Dimensions      = 1;
        block.Dwork(1).DatatypeID      = 0;      % double
        block.Dwork(1).Complexity      = 'Real'; % real
        block.Dwork(1).UsedAsDiscState = true;

      function InitializeConditions(block)

      function Start(block)

      block.Dwork(1).Data = 0;

      function Outputs(block)
      IPADDR = '128.1.1.101';
      tcpip_pipe1=tcpip(IPADDR, block.InputPort(1).Data);
      set(tcpip_pipe1, 'InputBufferSize', 4000); 
      tcpip_pipe1.ByteOrder='bigEndian';
      fopen(tcpip_pipe1);
      while ~strcmp(tcpip_pipe1.Status,'open'),end
      message = [...
          %*** TRANSACTION ID ***%
          uint8(0); uint8(3); ... % Two byte transaction ID
          %*** PROTOCOL ***%
          uint8(0); uint8(0); ... % Two byte protocol ID - all zeros means Modbus TCP
          %*** BYTES REMAINING ***%
          uint8(0); uint8(6); ... % Two byte number of bytes for everything after this
          %*** SLAVE ID ***%
          uint8(255); ... % Slave ID - use if end device is after a modbus tcp/rtu router, otherwise use 255
          %*** FUNCTION ID ***%
          uint8(4); ... % 4 - read input registers
          %*** DATA ***%
          %***** Starting Register *****%
          uint8(0); uint8(6); ... % Two byte number that gives the starting register to read
          %***** Number of Registers to Read *****%
          uint8(0); uint8(12)];   % Two byte number that gives how many registers to read
      fwrite(tcpip_pipe1, message,'int8');
      while ~tcpip_pipe1.BytesAvailable,end
      response = fread(tcpip_pipe1,tcpip_pipe1.BytesAvailable);
      block.OutputPort(1).Data = (response(10)*256+response(11))/1000;
      block.OutputPort(2).Data = (response(12)*256+response(13))/1000;
      block.OutputPort(3).Data = (response(14)*256+response(15))/1000;
      block.OutputPort(4).Data = (response(16)*256+response(17))/1000;
      fclose(tcpip_pipe1);
      delete(tcpip_pipe1);
      clear;
      %end Outputs

      function Update(block)

      block.Dwork(1).Data = block.OutputPort(1).Data;

      function Derivatives(block)

      %end Derivatives

      function Terminate(block)

      %end Terminate

[Jordan Ross]

Hi Tim,

When you do terminate the simulation does it always get the following error:

"Error evaluating registered method 'Outputs' of MATLAB S-Function 'Read_Analog_IO_1' in 'AVN_COD_control/Analog_IO_1/Level-2 MATLAB S-Function'"

If so, you might have a corner case in which your while loops are becoming infinite loops.

[NN]

i am also facing similar issue while running simulink file of power system.How can i know which loop is creating issue and how can i correct such an infinite loop if there is any ?please advice.