FB_MDP_Read 1:

The function block enables querying of an IPC diagnostics module element.


      : BOOL;             (* Function block execution is triggered by a rising edge at this input.*)
    stMDP_DynAddr : ST_MDP_Addr;
    pDstBuf       : DWORD;            (* Contains the address of the buffer for the received data. *)
    cbDstBufLen   : UDINT;            (* Contains the max. number of bytes to be received. *)
    tTimeout      : TIME := DEFAULT_ADS_TIMEOUT; (* States the time before the function is cancelled. *)
    sAmsNetId     : T_AmsNetId;       (* keep empty '' for the local device *)

bExecute: The function block is called by a rising edge on the input bExecute, if the block is not already active.

stMDP_DynAddr: The MDP addressing belonging to the selected network module is specified at this input. The structure is of the type ST_MDP_Addr. The dynamic Module ID must already be specified with it.

pDstBuf: The memory address of the data buffer is specified at this input. The received data are stored there if the query is successful.

cbDstBufLen: The length of the data buffer in bytes is specified at this input.

tTimeout: Specifies a maximum length of time for the execution of the function block.

sAmsNetId: To execute the query on the local device, it is not necessary to specify this input variable. Alternatively, an empty string can be specified. To direct the query to another computer, its AMS Net Id (of type T_AmsNetId) can be specified here.


   : BOOL;
    bError  : BOOL;
    nErrId  : UDINT;
    nCount  : UDINT;

bBusy: This output is TRUE as long as the function block is active.

bError: Becomes TRUE as soon as an error situation occurs.

nErrID: Returns an error code if the bError output is set.

nCount: This output indicates the number of bytes read.


Development environment

Target platform

PLC libraries to include

TwinCAT v3.1.0

PC or CX (x86, x64, ARM)