Cosim of C++ and Eplus

Source: vignettes/cpp.Rmd

This document show how to specify the path of .exe(C++ application) and conduct co-simulation with EnergyPlus .

Here is the C++ code

/*
 This C++ script is the example of CosimR to show how to do co-simulation with EnergyPlus
 The Code is messy because I'm not familiar with the C/C++. 
 You can open a issue and point how to modify it or make it clean.
 Package: CosimR
 Github:    https://github.com/jywang2016/CosimR
 Author: Jiangyu Wang
 Date: 11th Dec, 2018
 Email: jywang_2016@hust.edu.cn
 Reference: schedule example in BCVTB
 Compile: g++ -o Cosim Cosim.cpp -std=c++11
 */
#include <iostream>
#include <string>
#include <regex>
#include <stdio.h>
#include <stdlib.h>

using namespace std;

int main(int argc, char *argv[]){
  
  string error = "the Number of arguments are not correct!";
  if(argc !=4){
    cout<<error<<endl;
    return(1);
  }
  
  smatch result;
  string tempstr = argv[1];
  
  string regex_str("\\d+\\.?\\d*"); 
  regex pat(regex_str,regex::icase);
  
  string::const_iterator iter = tempstr.begin();
  string::const_iterator iterEnd= tempstr.end();
  string strouttemp;
  
  if(regex_search(iter,iterEnd,result,pat)){
    strouttemp = result[0]; //just need the first temperature info
    //cout<<outdoortemp<<endl;
  }
  
  int time;
  char *strtime = (char *) argv[2];
  time = atoi(strtime);
  
  float outtemp;
  char *strtemp = (char *) strouttemp.c_str();
  outtemp = atof(strtemp);
  
  // input const 
  const int DAYSTART = 6*3600;
  const int NIGHTSTART = 16*3600;
  const double TCNIGHT = 30.0;
  const double TCROOLOW = 22.0;
  const double TCROOHIG = 26.0;
  
  const double TCOUTLOW = 20.0;
  const double TCOUTHIG = 24.0;
  
  const double THDAY = 20.0;
  const double THNIGHT = 16.0;
  
  // temp set logic 
  
  double ToutDif;
  ToutDif = outtemp - TCOUTLOW;
  
  double TSetCooOn;
  TSetCooOn = TCROOLOW + ToutDif * (TCROOHIG - TCROOLOW)/(TCOUTHIG - TCOUTLOW);
  
  double TCDay;
  TCDay = max(TCROOLOW,min(TCROOHIG,TSetCooOn));
  
  double THSetPoi;
  double TCSetPoi;
  
  int timeOfDay = time % 86400;
  
  if(timeOfDay > DAYSTART && timeOfDay < NIGHTSTART){
    THSetPoi = THDAY;
    TCSetPoi = TCDay;
  }else{
    THSetPoi = THNIGHT;
    TCSetPoi = TCNIGHT;
  }
  
  cout<<THSetPoi<<","<<TCSetPoi<<", "<<endl;
  
  return 0;
}

Suppose the Cosim.cpp will be placed into the cpp folder under the xmlpath = 'D:/bcvtb/examples/CosimRtest'. If you are a R user with Rtools installed or Linux user, you can use g++ -o Cosim Cosim.cpp -std=c++11 to compile your codes. Then, place the Cosim.exe file into the ./cpp folder.

Co-simulation by using CosimR

library(CosimR)

Step1: generate the .xml file

## CosimR.xml is copied to D:/bcvtb/examples/CosimRtest successfully!

Step2: modify the .xml file

file.copy(from = system.file("extdata/Cosim.exe", package = "CosimR"),
          to = paste0(xmlpath,'/cpp'),
          overwrite = TRUE)
## [1] TRUE
## Part1: Cosim time set modify >>>>>>>>>
## timeStep: 900 beginTime: 259200 endTime: 345600
## Part2: ArrayExtract actor pram.args modify >>>>>>>>>
## extractLength: 2 outputArrayLength: 2
## Part3: EnergyPlus Simulator pram.args modify >>>>>>>>>
## energyplus command: " -w D:/bcvtb/examples/ePlusWeather/USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw -p eplusout -s C -x -m -r D:/bcvtb/examples/CosimRtest/SmOffPSZ.idf "
## Part4: SystemCommand pram.args modify >>>>>>>>>
## programname: D:/bcvtb/examples/CosimRtest/cpp/Cosim 
## programArgs: " $input $time $iteration" 
## workingDir: D:/bcvtb/examples/CosimRtest/cpp 
## simulationLog: D:/bcvtb/examples/CosimRtest/cpp/simulation.log
## ---------------- Modification End ----------------

Step3: save the .xml file

## new.xml is written successfully!

Step4: run the .xml file

Add plotter in BCVTB manually

Plotter block is not included in the .xml template file provided in the CosimR package. If you want see the results in real time, add plotter block in BCVTB manually is a good choice.