How to start/restart PLC using Twincat3 (error 1793)

Question

Following the advice to the question ( TwinCAT 3.0 Automation Interface without Visual Studio? ) I receive 1793 error (Service is not supported by server).

I try to write program to start/restart/config Beckhoff PLC using Twincat3 (this is the same functionality like the small Beckhoff GUI application). I'm trying to follow advices from solution presented above, but it seems that I cannot set the state. Reading values from the device works:

nPort = AdsPortOpen();
nErr = AdsGetLocalAddress(pAddr);
if (nErr) 
    cerr << "Error: AdsGetLocalAddress: " << nErr << '\n';

// TwinCAT 3 PLC1 = 851
pAddr->port = 10000;// 10000 as advised @ stackoverflow;

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_CONFIG;
    break;
    }
    nErr = AdsSyncReadStateReq(pAddr, &nAdsState, &nDeviceState);// , 0, pData);
    if (nErr) cerr << "Error: AdsSyncReadStateReq: " << nErr << '\n';

    cout << nAdsState << " " << nDeviceState << endl;

    nErr = AdsSyncWriteControlReq(pAddr, nAdsState, nDeviceState, 0, pData);
    if (nErr) cerr << "Error: AdsSyncWriteControlReq: " << nErr << '\n'; //1793
    ch = _getch();
    ch = toupper(ch);
}

Answer 1

Ok, I have found the solution, maybe someone will find it useful. There is no error in the code above, but required AdsState is wrong. It seems that ADSSTATE_RUN and ADSSTATE_CONFIG (and some others in this enum) are used only to return the state.

To actually change the state of device you should use ADSSTATE_RESET and ADSSTATE_RECONFIG (those two values reflect the functionality of start/restart in run mode and config mode). Also with ADSSTATE_STOP you can completely stop PLC, while ADSSTATE_SHUTDOWN allows for rebooting or turning off the PC (depending on DeviceState value 0/1).