Are RPC Methods available using the C DLL?

[chrisbeardy]

Hello, does anyone know if using the C DLL it is possible to do RPC method call of Methods from PLC FB's, like you can in the .NETimplementation?

I have had a look around the C files and can't see anything obvious, I'm not sure if it is possible to get the symbol of the method and just do a read/write to the correct memory areas.?

I ask this as I would like to be able to add this feature into the popular pyads package.

[dayaftereh]

Hey,

a working example to call a method can be found at infosys.

Example:

typedef struct
{
    unsigned long a;
    unsigned long b;
} MethodParameters;

// ...

long nErr, nPort;
AmsAddr Addr;
PAmsAddr pAddr = &Addr;
ULONG lHdlVar, rValue;
char szVar[] = {"MAIN.foo#DoAdd"};
MethodParameters params;

// ...

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

pAddr->port = 851;

nErr = AdsSyncReadWriteReq(pAddr, ADSIGRP_SYM_HNDBYNAME, 0x0, sizeof(lHdlVar), &lHdlVar, sizeof(szVar), szVar);
if (nErr)
{
    cerr << "Error: AdsSyncReadWriteReq: " << nErr << '\n';
}

params.a = 5;
params.b = 5;

nErr = AdsSyncReadWriteReq(pAddr, ADSIGRP_SYM_VALBYHND, lHdlVar, sizeof(rValue), &rValue, sizeof(params), &params);
if (nErr)
{
    cerr << "Error: AdsSyncReadWriteReq: " << nErr << '\n';
}

cout << "rValue: " << rValue;

nErr = AdsSyncWriteReq(pAddr, ADSIGRP_SYM_RELEASEHND, 0, sizeof(lHdlVar), &lHdlVar);
if (nErr)
{
    cerr << "Error: AdsSyncWriteReq: " << nErr << '\n';
}

nErr = AdsPortClose();
if (nErr)
{
    cerr << "Error: AdsPortClose: " << nErr << '\n';
}

[chrisbeardy]

this looks great, thanks. Can you repost the link please, its linking to:

and I cant seem to find that example

[dayaftereh]

Yes:

https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_adssamples_net/18014399555831179.html&id=713341834445367571

I found the example under TwinCAT ADS .NET Samples -> Samples ADS .NET -> PLC method call

[chrisbeardy]

awesome thank you