How to read a struct containing array of structs from TwinCat to C#

How to read a struct containing array of structs from TwinCat to C#

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How to read a struct containing array of structs from TwinCat to C#
Tag : chash , By : nseibert
Date : November 24 2020, 12:01 PM

I hope this helps . Using TwinCAT 3 ADS.Net for reading from PLC, I'm trying to read a struct containing array of structs, but the ReadAny command crashes with "Unable to marshal type" exception. , I tested successfully following code:
c# code:
    class Program
        public static TcAdsClient client;
        static void Main(string[] args)

            // Create the ADS Client
            using (client = new TcAdsClient())
                // Establish Connection
                client.Connect(new AmsAddress("", 851));
                int handle = client.CreateVariableHandle("PRG_AIS.stAds");

                AdsClass ads = (AdsClass)client.ReadAny(handle, typeof(AdsClass));
                ads.boolArr[0] = 1;
                client.WriteAny(handle, ads);


    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    class AdsClass

        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
        public byte[] boolArr = new byte[10];
TYPE AdsStruct :
    bTestArray : ARRAY[0..9] OF BOOL;
[StructLayout(LayoutKind.Sequential, Pack = 1)]
class AdsClass

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
    public InnerStruct[] strArr = new InnerStruct[10];

struct InnerStruct
    public byte bBoolTest;
    public int nIntTest;
TYPE AdsStruct  :
    stTestArray : ARRAY[0..9] OF InnerStruct;

TYPE InnerStruct :
    bBoolTest : BOOL;
    nIntTest  : DINT;

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Coldfusion 8: Array of structs to struct of structs

Tag : arrays , By : Francis
Date : March 29 2020, 07:55 AM
should help you out You will still need to convert to unixtime, but ArrayOfStructsSort might be faster. At least you can compare the two options.

passing an argument ( a struct in an array of structs within a struct) to a function in C

Tag : c , By : Sebastián Ucedo
Date : March 29 2020, 07:55 AM
it should still fix some issue I have a struct "course" and a function for it: , Change:
typedef struct Transcript_s
    char* name;
    struct Course** courseArray;
} Transcript;
typedef struct Transcript_s
    char* name;
    Course** courseArray; /* 'Course' is a typedef for 'struct Course_s'. */
} Transcript;
t -> courseArray = malloc(sizeof(struct Course) * (a+1));
t -> courseArray = malloc(sizeof(Course*) * (a+1));
free(t -> courseArray);
while (t->courseArray[a] != NULL)
    free(t->courseArray[a]->name); /* If name was dynamically allocated. */
free(t -> courseArray);

How to properly allocate memory for structs, arrays of structs inside a struct, and passing that array as a parameter

Tag : c , By : pepper
Date : March 29 2020, 07:55 AM
Hope that helps There is no struct S, only S which is a typedef of anonymous structure.
Define struct S too:
typedef struct S {
  char id;
  struct S *children[SIZE];
typedef struct S S;
struct S {
  char id;
  S *children[SIZE];
arr[0].children[0] = malloc(sizeof(S));

Write array of struct using TwinCAT.Ads through C# application

Tag : chash , By : dnyaneshwar
Date : March 29 2020, 07:55 AM
I hope this helps you . I guess you are missing the counterpart in the PLC. Please make sure that in your PLC you have declared an array of stations something like:
// I have it in a global variable list named: STG_Variables
stat_array_Var : array [0..5] of Station;
TcAdsClient AdsComClient = new TcAdsClient();
AdsComClient.Connect(NetID_TwinCat, 851);

int handle_array = AdsComClient.CreateVariableHandle("STG_Variables.stat_array_Var");

// get some test stations:
Station station = new Station();
Station station2 = new Station();
Station station3 = new Station();
Station station4 = new Station();
Station station5 = new Station();

Station[] station_plural = new Station[] { station, station2, station3, station4, station5 };

// write some stuff to recognize that write test worked
for (int i = 0; i < station_plural.Length; i++)
    station_plural[i].ClusterID = "ID: " + i.ToString();

// just use the normal WriteAny method without the new int[] { 5 } parameter!
// send it down to the plc
AdsComClient.WriteAny(handle_array, plural);
[StructLayout(LayoutKind.Sequential, Pack = 0)]
public class Station
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 11)]
    public string ClusterID;
    public byte Tech_Type;
    public bool Status;
    public bool Reject;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 51)]
    public string Rej_Detail;
    public byte Rej_Catagory;
TYPE Station :
    ClusterID   : STRING[10];
    Tech_Type   : USINT;
    Status      : BOOL;
    Reject      : BOOL;
    Rej_Detail  : STRING[50];
    Rej_Catagory : USINT; 

Write array of struct using TwinCAT.Ads through vb.net application

Tag : .net , By : John Q.
Date : March 29 2020, 07:55 AM
I wish did fix the issue. A reference for those who are having similar problems: The difference in data type for TwinCAT and VB can be found in Beckhoff website: https://infosys.beckhoff.com/english.php?content=../content/1033/tcsystemmanager/basics/TcSysMgr_DatatypeComparison.htm&id=
TwinCAT is using IEC61131-3 standard.
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