Start/stop PLC

The following program starts or stops run-time system 1 in the PLC.
#include <iostream.h>
#include <windows.h>
#include <conio.h>

// ADS headers for TwinCAT 3
#include "C:\TwinCAT\AdsApi\TcAdsDll\Include\TcAdsDef.h"
#include "C:\TwinCAT\AdsApi\TcAdsDll\Include\TcAdsAPI.h"

void main()
{
 USHORT nAdsState;
 USHORT nDeviceState = 0;
 long    nErr, nPort;
 int     ch;
 void    *pData = NULL;
 AmsAddr Addr;
 PAmsAddr pAddr = &Addr;

 // Open communication port on the ADS router
 nPort = AdsPortOpen();
 nErr = AdsGetLocalAddress(pAddr);
 if (nErr) cerr << "Error: AdsGetLocalAddress: " << nErr << '\n';
 
 // TwinCAT 3 PLC1 = 851
 pAddr->port = 851;

 cout << "(R) -> PLC Run\n";
 cout << "(S) -> PLC Stop\n";
 cout.flush();
 ch = getch();
 ch = toupper(ch);
 while ( (ch == 'R') || (ch == 'S') )
 {
 switch (ch)
 {
 case 'R':
    nAdsState = ADSSTATE_RUN;
    break;
 case 'S':
    nAdsState = ADSSTATE_STOP;
    break;
 }
 nErr = AdsSyncWriteControlReq (pAddr, nAdsState, nDeviceState, 0, pData);
 if (nErr) cerr << "Error: AdsSyncWriteControlReq: " << nErr << '\n';
 ch = getch();
 ch = toupper(ch);
 }

 // Close communication port
 nErr = AdsPortClose();
 if (nErr) cerr << "Error: AdsPortClose: " << nErr << '\n';
}