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[TRNSYS-users] Convergence error with Type 56 and Type 23



Hello,

 

I’m having a convergence error that seems to be rooted in the PID controller.  I was wondering if anyone could shed some light on the subject.

 

I’m trying to model a long-haul truck sleeper cabin climate control system.  I’m using a Type 23 PID controller in conjunction with a “seasonal switch” as the climate control unit.  The purpose of the seasonal switch is to  turn the heater on and the air conditioner off when the temperature drops below some low deadband temperature and vice versa when the temperature rises above the high deadband temperature.  In other words, the purpose of this switch is to keep the air conditioner from coming on during slight over-heating and the heater from coming on during slight over-cooling.  The deadband in the seasonal switch is set by default to 5 degrees Celsius. 

 

When just this group of components is run, the output signal from the PID controller and seasonal switch match just as they should (climate controller.tpf).  However, when a fuel-fired heater (Type 151, homegrown) is added, the control signal starts doing some crazy stuff (Climate controller with heater.tpf).  The control signals, which should align nicely, start diverging considerably.  This (I assume) creates the convergence error that stops the simulation after a little more than an hour with the current settings.    

 

Is there something inherent in the way I am trying to string together these components that is making the solver diverge?  Is there a better way to go about it?  I’m not looking for a total solution- simply a pointer or two towards why the program is behaving as it is and what I might do to get back on track.  Please let me know if you need any other files. 

 

Thank you in advance for your time,

Ethan Lust

301.405.8672 (desk)

757.636.8727 (cell)

University of Maryland

			SUBROUTINE TYPE151 (TIME,XIN,OUT,T,DTDT,PAR,INFO,ICNTRL,*) 
C************************************************************************
C Object: Espar D2/D4 direct-fired space heater 
C Simulation Studio Model: Type151
C 
C Author: Ethan Lust
C Editor: 
C Date:	 March 31, 2008 last modified: April 1, 2008
C 
C 
C *** 
C *** Model Parameters 
C *** 
C			model	- [2;4]
C			system_voltage	V [0;+Inf]

C *** 
C *** Model Inputs 
C *** 
C			control_input	- [0;+Inf]

C *** 
C *** Model Outputs 
C *** 
C			heat_output	kJ/hr [0;+Inf]
C			fuel_consumption	l/hr [0;+Inf]
C			air_flow_rate	m^3/s [0;+Inf]
C           power_draw

C *** 
C *** Model Derivatives 
C *** 

C (Comments and routine interface generated by TRNSYS Studio)
C************************************************************************

C    TRNSYS acess functions (allow to acess TIME etc.) 
      USE TrnsysConstants
      USE TrnsysFunctions

C-----------------------------------------------------------------------------------------------------------------------
C    REQUIRED BY THE MULTI-DLL VERSION OF TRNSYS
      !DEC$ATTRIBUTES DLLEXPORT :: TYPE151				!SET THE CORRECT TYPE NUMBER HERE
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    TRNSYS DECLARATIONS
      IMPLICIT NONE			!REQUIRES THE USER TO DEFINE ALL VARIABLES BEFORE USING THEM

	DOUBLE PRECISION XIN	!THE ARRAY FROM WHICH THE INPUTS TO THIS TYPE WILL BE RETRIEVED
	DOUBLE PRECISION OUT	!THE ARRAY WHICH WILL BE USED TO STORE THE OUTPUTS FROM THIS TYPE
	DOUBLE PRECISION TIME	!THE CURRENT SIMULATION TIME - YOU MAY USE THIS VARIABLE BUT DO NOT SET IT!
	DOUBLE PRECISION PAR	!THE ARRAY FROM WHICH THE PARAMETERS FOR THIS TYPE WILL BE RETRIEVED
	DOUBLE PRECISION STORED !THE STORAGE ARRAY FOR HOLDING VARIABLES FROM TIMESTEP TO TIMESTEP
	DOUBLE PRECISION T		!AN ARRAY CONTAINING THE RESULTS FROM THE DIFFERENTIAL EQUATION SOLVER
	DOUBLE PRECISION DTDT	!AN ARRAY CONTAINING THE DERIVATIVES TO BE PASSED TO THE DIFF.EQ. SOLVER
	INTEGER*4 INFO(15)		!THE INFO ARRAY STORES AND PASSES VALUABLE INFORMATION TO AND FROM THIS TYPE
	INTEGER*4 NP,NI,NOUT,ND	!VARIABLES FOR THE MAXIMUM NUMBER OF PARAMETERS,INPUTS,OUTPUTS AND DERIVATIVES
	INTEGER*4 NPAR,NIN,NDER	!VARIABLES FOR THE CORRECT NUMBER OF PARAMETERS,INPUTS,OUTPUTS AND DERIVATIVES
	INTEGER*4 IUNIT,ITYPE	!THE UNIT NUMBER AND TYPE NUMBER FOR THIS COMPONENT
	INTEGER*4 ICNTRL		    !AN ARRAY FOR HOLDING VALUES OF CONTROL FUNCTIONS WITH THE NEW SOLVER
	INTEGER*4 NSTORED		!THE NUMBER OF VARIABLES THAT WILL BE PASSED INTO AND OUT OF STORAGE
	CHARACTER*3 OCHECK		!AN ARRAY TO BE FILLED WITH THE CORRECT VARIABLE TYPES FOR THE OUTPUTS
	CHARACTER*3 YCHECK		!AN ARRAY TO BE FILLED WITH THE CORRECT VARIABLE TYPES FOR THE INPUTS
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    USER DECLARATIONS - SET THE MAXIMUM NUMBER OF PARAMETERS (NP), INPUTS (NI),
C    OUTPUTS (NOUT), AND DERIVATIVES (ND) THAT MAY BE SUPPLIED FOR THIS TYPE
      PARAMETER (NP=2,NI=1,NOUT=4,ND=0,NSTORED=0)
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    REQUIRED TRNSYS DIMENSIONS
      DIMENSION XIN(NI),OUT(NOUT),PAR(NP),YCHECK(NI),OCHECK(NOUT),
	1   STORED(NSTORED),T(ND),DTDT(ND)
      INTEGER NITEMS
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    ADD DECLARATIONS AND DEFINITIONS FOR THE USER-VARIABLES HERE


C    PARAMETERS
      INTEGER model
      INTEGER system_voltage

C    INPUTS
      DOUBLE PRECISION control_input
      
C    OUTPUTS
      DOUBLE PRECISION heat_output
      DOUBLE PRECISION fuel_consumption
      DOUBLE PRECISION air_flow_rate
      DOUBLE PRECISION power_draw
      
C-----------------------------------------------------------------------------------------------------------------------
C       READ IN THE VALUES OF THE PARAMETERS IN SEQUENTIAL ORDER
      model=PAR(1)
      system_voltage=PAR(2)

C-----------------------------------------------------------------------------------------------------------------------
C    RETRIEVE THE CURRENT VALUES OF THE INPUTS TO THIS MODEL FROM THE XIN ARRAY IN SEQUENTIAL ORDER

      control_input=XIN(1)
	   IUNIT=INFO(1)
	   ITYPE=INFO(2)

C-----------------------------------------------------------------------------------------------------------------------
C    SET THE VERSION INFORMATION FOR TRNSYS
      IF(INFO(7).EQ.-2) THEN
	   INFO(12)=16
	   RETURN 1
	ENDIF
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    DO ALL THE VERY LAST CALL OF THE SIMULATION MANIPULATIONS HERE
      IF (INFO(8).EQ.-1) THEN
	   RETURN 1
	ENDIF
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    PERFORM ANY 'AFTER-ITERATION' MANIPULATIONS THAT ARE REQUIRED HERE
C    e.g. save variables to storage array for the next timestep
      IF (INFO(13).GT.0) THEN
	   NITEMS=0
C	   STORED(1)=... (if NITEMS > 0)
C        CALL setStorageVars(STORED,NITEMS,INFO)
	   RETURN 1
	ENDIF
C
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    DO ALL THE VERY FIRST CALL OF THE SIMULATION MANIPULATIONS HERE
      IF (INFO(7).EQ.-1) THEN

C       SET SOME INFO ARRAY VARIABLES TO TELL THE TRNSYS ENGINE HOW THIS TYPE IS TO WORK
         INFO(6)=NOUT				
         INFO(9)=1				
	   INFO(10)=0	!STORAGE FOR VERSION 16 HAS BEEN CHANGED				

C       SET THE REQUIRED NUMBER OF INPUTS, PARAMETERS AND DERIVATIVES THAT THE USER SHOULD SUPPLY IN THE INPUT FILE
C       IN SOME CASES, THE NUMBER OF VARIABLES MAY DEPEND ON THE VALUE OF PARAMETERS TO THIS MODEL....
         NIN=NI
	   NPAR=NP
	   NDER=ND
	       
C       CALL THE TYPE CHECK SUBROUTINE TO COMPARE WHAT THIS COMPONENT REQUIRES TO WHAT IS SUPPLIED IN 
C       THE TRNSYS INPUT FILE
	   CALL TYPECK(1,INFO,NIN,NPAR,NDER)

C       SET THE NUMBER OF STORAGE SPOTS NEEDED FOR THIS COMPONENT
         NITEMS=0
C	   CALL setStorageSize(NITEMS,INFO)

C       RETURN TO THE CALLING PROGRAM
         RETURN 1

      ENDIF
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    DO ALL OF THE INITIAL TIMESTEP MANIPULATIONS HERE - THERE ARE NO ITERATIONS AT THE INTIAL TIME
      IF (TIME .LT. (getSimulationStartTime() +
     . getSimulationTimeStep()/2.D0)) THEN

C       SET THE UNIT NUMBER FOR FUTURE CALLS
         IUNIT=INFO(1)
         ITYPE=INFO(2)

C       CHECK THE PARAMETERS FOR PROBLEMS AND RETURN FROM THE SUBROUTINE IF AN ERROR IS FOUND
C         IF(...) CALL TYPECK(-4,INFO,0,"BAD PARAMETER #",0)

C       PERFORM ANY REQUIRED CALCULATIONS TO SET THE INITIAL VALUES OF THE OUTPUTS HERE
C		 heat_output
			OUT(1)=0
C		 fuel_consumption
			OUT(2)=0
C		 air_flow_rate
			OUT(3)=0
C        power_draw
            OUT(4)=0

C       PERFORM ANY REQUIRED CALCULATIONS TO SET THE INITIAL STORAGE VARIABLES HERE
         NITEMS=0
C	   STORED(1)=...

C       PUT THE STORED ARRAY IN THE GLOBAL STORED ARRAY
C         CALL setStorageVars(STORED,NITEMS,INFO)

C       RETURN TO THE CALLING PROGRAM
         RETURN 1

      ENDIF
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C    *** ITS AN ITERATIVE CALL TO THIS COMPONENT ***
C-----------------------------------------------------------------------------------------------------------------------

	    
C-----------------------------------------------------------------------------------------------------------------------
C    RETRIEVE THE VALUES IN THE STORAGE ARRAY FOR THIS ITERATION
C      NITEMS=
C	CALL getStorageVars(STORED,NITEMS,INFO)
C      STORED(1)=
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    CHECK THE INPUTS FOR PROBLEMS
C      IF(...) CALL TYPECK(-3,INFO,'BAD INPUT #',0,0)
C	IF(IERROR.GT.0) RETURN 1
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    *** PERFORM ALL THE CALCULATION HERE FOR THIS MODEL. ***
C-----------------------------------------------------------------------------------------------------------------------

C		ADD YOUR COMPONENT EQUATIONS HERE; BASICALLY THE EQUATIONS THAT WILL
C		CALCULATE THE OUTPUTS BASED ON THE PARAMETERS AND THE INPUTS.	REFER TO
C		CHAPTER 3 OF THE TRNSYS VOLUME 1 MANUAL FOR DETAILED INFORMATION ON
C		WRITING TRNSYS COMPONENTS.

!Assumptions
!*startup power is negligable over long time scales
      
!D2 Output calculations

      IF (model .EQ. 2) THEN
	
	  IF (control_input .GT. 0 .AND. control_input .LE. .25) THEN                   !low

		    heat_output = 3060 					            !(kJ/hr)

			    IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*0.7*3.6 	!(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*0.3*3.6	    !(kJ/hr)

			    END IF		

		    fuel_consumption = 0.10 				        !(L/hr)	

		    air_flow_rate = 0.008968 				        !(m^3/s)

	  ELSE IF (control_input .GT.0.25 .AND. control_input .LE. 0.5) THEN             	!medium

		     heat_output = 4320 					        !(kJ/hr)

		         IF (system_voltage .EQ. 12) THEN

		            power_draw = system_voltage*1.0*3.6 	!(kJ/hr)

			     ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*0.5*3.6	    !(kJ/hr)

			     END IF			


		    fuel_consumption = 0.14 				        !(L/hr)	
      
		    air_flow_rate = 0.012744 				        !(m^3/s)

	  ELSE IF (control_input .GT. 0.5 .AND. control_input .LE. 0.75) THEN             !high

		    heat_output = 6480 					            !(kJ/hr)

		        IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*1.9*3.6 	!(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*1.0*3.6	    !(kJ/hr)

			    END IF			

		    fuel_consumption = 0.23 				        !(L/hr)	

		    air_flow_rate = 0.01888 				        !(m^3/s)

	   ELSE IF (control_input .GT. 0.75 .AND. control_input .LE. 1) THEN            !boost

		    heat_output = 7920 					            !(kJ/hr)

		        IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*1.4*3.6 	!(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*2.8*3.6	    !(kJ/hr)

			    END IF

      		fuel_consumption = 0.28 				        !(L/hr)	

	  	air_flow_rate = 0.022656 				        !(m^3/s)
	
	   ELSE                                              !off
		
		    heat_output = 0 						        !(kJ/hr)
		
		    power_draw = 0 						            !(kJ/hr)

		    fuel_consumption = 0 					        !(L/hr)	

		    air_flow_rate = 0 					            !(m^3/s)
		
         END IF	
			
	END IF

!D4 Output calculations
      
      IF (model .EQ. 4) THEN
		
	  IF (control_input .GT. 0 .AND. control_input .LE. .25) THEN                    !low

		    heat_output = 3600 					             !(kJ/hr)

			    IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*0.6*3.6 	 !(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*0.3*3.6	     !(kJ/hr)

			    END IF

		    fuel_consumption = 0.13 				         !(L/hr)	

		    air_flow_rate = 0.01416 				         !(m^3/s)

	  ELSE IF (control_input .GT. .25 .AND. control_input .LE. 0.5) THEN              !medium

		    heat_output = 7200 					             !(kJ/hr)

		        IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*1.1*3.6 	 !(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*0.5*3.6	     !(kJ/hr)

			    END IF			

		    fuel_consumption = 0.25 				         !(L/hr)	

		    air_flow_rate = 0.0236	   				         !(m^3/s)
		    
	  ELSE IF (control_input .GT. 0.5 .AND. control_input .LE. 0.75) THEN              !high

		    heat_output = 10800 					         !(kJ/hr)

		        IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*2.0*3.6 	 !(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*1.0*3.6	     !(kJ/hr)

			    END IF

		    fuel_consumption = 0.38 				         !(L/hr)	

		    air_flow_rate = 0.032568 				         !(m^3/s)

	  ELSE IF (control_input .GT. 0.75 .AND. control_input .LE. 1) THEN              !boost

		    heat_output = 14400 					         !(kJ/hr)

		        IF (system_voltage .EQ. 12) THEN

				    power_draw = system_voltage*3.3*3.6 	 !(kJ/hr)

			    ELSE IF (system_voltage .EQ. 24) THEN 

				    power_draw = system_voltage*1.7*3.6	     !(kJ/hr)

			    END IF


		    fuel_consumption = 0.51 				         !(L/hr)	

		    air_flow_rate = 0.04012					         !(m^3/s)

         ELSE                                               !off
		
		    heat_output = 0 					             !(kJ/hr)
		
		    power_draw = 0 						             !(kJ/hr)

		    fuel_consumption = 0 					         !(L/hr)	

		    air_flow_rate = 0 					             !(m^3/s)
		
		END IF

      END IF
           
C-----------------------------------------------------------------------------------------------------------------------

C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    SET THE STORAGE ARRAY AT THE END OF THIS ITERATION IF NECESSARY
C      NITEMS=
C      STORED(1)=
C	CALL setStorageVars(STORED,NITEMS,INFO)
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    REPORT ANY PROBLEMS THAT HAVE BEEN FOUND USING CALLS LIKE THIS:
C      CALL MESSAGES(-1,'put your message here','MESSAGE',IUNIT,ITYPE)
C      CALL MESSAGES(-1,'put your message here','WARNING',IUNIT,ITYPE)
C      CALL MESSAGES(-1,'put your message here','SEVERE',IUNIT,ITYPE)
C      CALL MESSAGES(-1,'put your message here','FATAL',IUNIT,ITYPE)
C-----------------------------------------------------------------------------------------------------------------------
C-----------------------------------------------------------------------------------------------------------------------
C    SET THE OUTPUTS FROM THIS MODEL IN SEQUENTIAL ORDER AND GET OUT

C		 heat_output
			OUT(1)=heat_output
C		 fuel_consumption
			OUT(2)=fuel_consumption
C		 air_flow_rate
			OUT(3)=air_flow_rate
C        power_draw
            OUT(4)=power_draw

C-----------------------------------------------------------------------------------------------------------------------
C    EVERYTHING IS DONE - RETURN FROM THIS SUBROUTINE AND MOVE ON
      RETURN 1
      END
C-----------------------------------------------------------------------------------------------------------------------
        SUBROUTINE TYPE200 (TIME,XIN,OUT,T,DTDT,PAR,INFO,ICNTRL,*) 
!************************************************************************
! Object: Seasonal Switch
! Simulation Studio Model: Type200
! 
! Author: Ethan Lust
! Editor: 
! Date:	 April 23, 2008 last modified: April 23, 2008
! 
! 
! *** 
! *** Model Parameters 
! *** 
!			setpoint	C [-Inf;+Inf]
!			deadband	C [0;+Inf]

! *** 
! *** Model Inputs 
! *** 
!			input_signal	- [-Inf;+Inf]
!			T_space	! [-Inf;+Inf]

! *** 
! *** Model Outputs 
! *** 
!			output_signal	- [-Inf;+Inf]
!			switch	- [0;1]

! *** 
! *** Model Derivatives 
! *** 

! (Comments and routine interface generated by TRNSYS Studio)
!************************************************************************

!    TRNSYS acess functions (allow to acess TIME etc.) 
      USE TrnsysConstants
      USE TrnsysFunctions

!-----------------------------------------------------------------------------------------------------------------------
!    REQUIRED BY THE MULTI-DLL VERSION OF TRNSYS
      !DEC$ATTRIBUTES DLLEXPORT :: TYPE200				!SET THE CORRECT TYPE NUMBER HERE
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    TRNSYS DECLARATIONS
      IMPLICIT NONE			!REQUIRES THE USER TO DEFINE ALL VARIABLES BEFORE USING THEM

	DOUBLE PRECISION XIN	!THE ARRAY FROM WHICH THE INPUTS TO THIS TYPE WILL BE RETRIEVED
	DOUBLE PRECISION OUT	!THE ARRAY WHICH WILL BE USED TO STORE THE OUTPUTS FROM THIS TYPE
	DOUBLE PRECISION TIME	!THE CURRENT SIMULATION TIME - YOU MAY USE THIS VARIABLE BUT DO NOT SET IT!
	DOUBLE PRECISION PAR	!THE ARRAY FROM WHICH THE PARAMETERS FOR THIS TYPE WILL BE RETRIEVED
	DOUBLE PRECISION STORED !THE STORAGE ARRAY FOR HOLDING VARIABLES FROM TIMESTEP TO TIMESTEP
	DOUBLE PRECISION T		!AN ARRAY CONTAINING THE RESULTS FROM THE DIFFERENTIAL EQUATION SOLVER
	DOUBLE PRECISION DTDT	!AN ARRAY CONTAINING THE DERIVATIVES TO BE PASSED TO THE DIFF.EQ. SOLVER
	INTEGER*4 INFO(15)		!THE INFO ARRAY STORES AND PASSES VALUABLE INFORMATION TO AND FROM THIS TYPE
	INTEGER*4 NP,NI,NOUT,ND	!VARIABLES FOR THE MAXIMUM NUMBER OF PARAMETERS,INPUTS,OUTPUTS AND DERIVATIVES
	INTEGER*4 NPAR,NIN,NDER	!VARIABLES FOR THE CORRECT NUMBER OF PARAMETERS,INPUTS,OUTPUTS AND DERIVATIVES
	INTEGER*4 IUNIT,ITYPE	!THE UNIT NUMBER AND TYPE NUMBER FOR THIS COMPONENT
	INTEGER*4 ICNTRL		!AN ARRAY FOR HOLDING VALUES OF CONTROL FUNCTIONS WITH THE NEW SOLVER
	INTEGER*4 NSTORED		!THE NUMBER OF VARIABLES THAT WILL BE PASSED INTO AND OUT OF STORAGE
	CHARACTER*3 OCHECK		!AN ARRAY TO BE FILLED WITH THE CORRECT VARIABLE TYPES FOR THE OUTPUTS
	CHARACTER*3 YCHECK		!AN ARRAY TO BE FILLED WITH THE CORRECT VARIABLE TYPES FOR THE INPUTS
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    USER DECLARATIONS - SET THE MAXIMUM NUMBER OF PARAMETERS (NP), INPUTS (NI),
!    OUTPUTS (NOUT), AND DERIVATIVES (ND) THAT MAY BE SUPPLIED FOR THIS TYPE
      PARAMETER (NP=2,NI=3,NOUT=2,ND=0,NSTORED=1)
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    REQUIRED TRNSYS DIMENSIONS
      DIMENSION XIN(NI),OUT(NOUT),PAR(NP),YCHECK(NI),OCHECK(NOUT),
	1   STORED(NSTORED),T(ND),DTDT(ND)
      INTEGER NITEMS
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    ADD DECLARATIONS AND DEFINITIONS FOR THE USER-VARIABLES HERE


!    PARAMETERS
      DOUBLE PRECISION setpoint
      DOUBLE PRECISION deadband

!    INPUTS
      DOUBLE PRECISION input_signal
      DOUBLE PRECISION T_space
      
!    OUTPUTS
      DOUBLE PRECISION output_signal
      DOUBLE PRECISION switch

!    LOCAL VARIABLE
      DOUBLE PRECISION error

!-----------------------------------------------------------------------------------------------------------------------
!       READ IN THE VALUES OF THE PARAMETERS IN SEQUENTIAL ORDER
      setpoint=PAR(1)
      deadband=PAR(2)

!-----------------------------------------------------------------------------------------------------------------------
!    RETRIEVE THE CURRENT VALUES OF THE INPUTS TO THIS MODEL FROM THE XIN ARRAY IN SEQUENTIAL ORDER

      input_signal=XIN(1)
      T_space = XIN(2)
      switch = XIN(3)
	   IUNIT=INFO(1)
	   ITYPE=INFO(2)

!-----------------------------------------------------------------------------------------------------------------------
!    SET THE VERSION INFORMATION FOR TRNSYS
      IF(INFO(7).EQ.-2) THEN
	   INFO(12)=16
	   RETURN 1
	ENDIF
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    DO ALL THE VERY LAST CALL OF THE SIMULATION MANIPULATIONS HERE
      IF (INFO(8).EQ.-1) THEN
	   RETURN 1
	ENDIF
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    PERFORM ANY 'AFTER-ITERATION' MANIPULATIONS THAT ARE REQUIRED HERE
!    e.g. save variables to storage array for the next timestep
!      IF (INFO(13).GT.0) THEN
!	   NITEMS=1
!	   STORED(1)= switch
!        CALL setStorageVars(STORED,NITEMS,INFO)
!	   RETURN 1
!	ENDIF
!
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    DO ALL THE VERY FIRST CALL OF THE SIMULATION MANIPULATIONS HERE
      IF (INFO(7).EQ.-1) THEN

!       SET SOME INFO ARRAY VARIABLES TO TELL THE TRNSYS ENGINE HOW THIS TYPE IS TO WORK
         INFO(6)=NOUT				
         INFO(9)=1				
	   INFO(10)=0	!STORAGE FOR VERSION 16 HAS BEEN CHANGED				

!       SET THE REQUIRED NUMBER OF INPUTS, PARAMETERS AND DERIVATIVES THAT THE USER SHOULD SUPPLY IN THE INPUT FILE
!       IN SOME CASES, THE NUMBER OF VARIABLES MAY DEPEND ON THE VALUE OF PARAMETERS TO THIS MODEL....
         NIN=NI
	   NPAR=NP
	   NDER=ND
	       
!       CALL THE TYPE CHECK SUBROUTINE TO COMPARE WHAT THIS COMPONENT REQUIRES TO WHAT IS SUPPLIED IN 
!       THE TRNSYS INPUT FILE
	   CALL TYPECK(1,INFO,NIN,NPAR,NDER)

!       SET THE NUMBER OF STORAGE SPOTS NEEDED FOR THIS COMPONENT
!         NITEMS=1
!	   CALL setStorageSize(NITEMS,INFO)

!       RETURN TO THE CALLING PROGRAM
         RETURN 1

      ENDIF
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    DO ALL OF THE INITIAL TIMESTEP MANIPULATIONS HERE - THERE ARE NO ITERATIONS AT THE INTIAL TIME
      IF (TIME .LT. (getSimulationStartTime() +
     . getSimulationTimeStep()/2.D0)) THEN

!       SET THE UNIT NUMBER FOR FUTURE CALLS
         IUNIT=INFO(1)
         ITYPE=INFO(2)

!       CHECK THE PARAMETERS FOR PROBLEMS AND RETURN FROM THE SUBROUTINE IF AN ERROR IS FOUND
!         IF(...) CALL TYPECK(-4,INFO,0,"BAD PARAMETER #",0)

!       PERFORM ANY REQUIRED CALCULATIONS TO SET THE INITIAL VALUES OF THE OUTPUTS HERE
!		 output_signal
			OUT(1)=0
!		 switch
!			OUT(2)=0

!       PERFORM ANY REQUIRED CALCULATIONS TO SET THE INITIAL STORAGE VARIABLES HERE
!         NITEMS=1
!	   STORED(1)= 0

!       PUT THE STORED ARRAY IN THE GLOBAL STORED ARRAY
!         CALL setStorageVars(STORED,NITEMS,INFO)

!       RETURN TO THE CALLING PROGRAM
         RETURN 1

      ENDIF
!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!    *** ITS AN ITERATIVE CALL TO THIS COMPONENT ***
!-----------------------------------------------------------------------------------------------------------------------

	    
!-----------------------------------------------------------------------------------------------------------------------
!    RETRIEVE THE VALUES IN THE STORAGE ARRAY FOR THIS ITERATION
!      NITEMS= 1
!	CALL getStorageVars(STORED,NITEMS,INFO)
!      STORED(1)= switch
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    CHECK THE INPUTS FOR PROBLEMS
!      IF(...) CALL TYPECK(-3,INFO,'BAD INPUT #',0,0)
!	IF(IERROR.GT.0) RETURN 1
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    *** PERFORM ALL THE CALCULATION HERE FOR THIS MODEL. ***
!-----------------------------------------------------------------------------------------------------------------------

      input_signal = abs(input_signal)
      
      error = setpoint - T_space

	if (switch .EQ. 0D0) then
        	if (error .LE. -deadband) then
            		switch = 1D0               !Turns A/C on and heat off
        	end if
      	else if (switch .EQ. 1D0) then
        	if (error .GE. deadband) then
            		switch = 0D0               !Turns heat on and A/C off
        	end if
      	end if
            
      	if (switch .EQ. 0D0) then
		    if (error .GE. 0) then
			    output_signal = input_signal
		    else if (error .LT. 0) then
			    output_signal = 0
		    end if
      	else if (switch .EQ. 1D0) then
		    if (error .LE. 0) then 
			    output_signal = -input_signal      
		    else if (error .GT. 0) then 
			    output_signal = 0
		    end if
      	end if

!-----------------------------------------------------------------------------------------------------------------------

!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    SET THE STORAGE ARRAY AT THE END OF THIS ITERATION IF NECESSARY
!      NITEMS= 1
!      STORED(1)= switch
!	CALL setStorageVars(STORED,NITEMS,INFO)
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    REPORT ANY PROBLEMS THAT HAVE BEEN FOUND USING CALLS LIKE THIS:
!      CALL MESSAGES(-1,'put your message here','MESSAGE',IUNIT,ITYPE)
!      CALL MESSAGES(-1,'put your message here','WARNING',IUNIT,ITYPE)
!      CALL MESSAGES(-1,'put your message here','SEVERE',IUNIT,ITYPE)
!      CALL MESSAGES(-1,'put your message here','FATAL',IUNIT,ITYPE)
!-----------------------------------------------------------------------------------------------------------------------
!-----------------------------------------------------------------------------------------------------------------------
!    SET THE OUTPUTS FROM THIS MODEL IN SEQUENTIAL ORDER AND GET OUT

!		 output_signal
			OUT(1) = output_signal
!		 switch
			OUT(2) = switch

!-----------------------------------------------------------------------------------------------------------------------
!    EVERYTHING IS DONE - RETURN FROM THIS SUBROUTINE AND MOVE ON
      RETURN 1
      END
!-----------------------------------------------------------------------------------------------------------------------

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