PLC

The PLC receives access to the variable memory areas from the PLC-Run-Time-System after starting the control. The memory is differed in channel and global area.

              pVE[iChannelNr]^.addr
              pVEGlob^.addr

To simplify the access to the variable area an additional library TcCncUtilities.lib exists. With functions out of this library, which takes over the management of the variables you can access the V.E.Variables by name (max 20 characters).

If external variables are configured with user defined variable types, the PLC library TcCncUtilities.lib cannot be used. In this case the variable structures should be recreated in the PLC to enable the direct access on the assigned V.E. variable memory by the pointers pVE[iChannelNr]^.addr respectively pVEGlob^.addr (see programming example 2).

Before using the different functions of the library, a basic initialization must be accomplished. During this initialization the format description defined in the CNC configuration is automatically transferred to the PLC.

For this propose the SPS and the CNC exchandes the V.E.Varibles descriptions. During the initialization the will, be cleared.

Additionally the memory ranges, indexes and data types of the different variables will be checked during the initialization. If an error occurs an error message in the Logger is generated. To prevent the access to non-defined storage area in arrays an examination of the memory addresses is carried out. That’s why the size of the data type is passed to the respective function of the library.

For the reading and writing access to the external variables or arrays of external variables pointers to the expected data type will be generated. This pointers in each case will be initialized with the associated address of the variable in HLI memory range. After that you can access the variable with the dereferenced pointer from the PLC.

F.e.:

POINTER_TO_BOOL = VeBool(1, 'Peter', 0);
POINTER_TO_BOOL^=23;

The following example refers on the V.E. configuration from this documentation (see text above chapter Syntax (from Version V254 onwards)). Before accessing the V.E. variables in a program the HLI interface should be initialized (see [HLI Interface]), TcCncUtilities.lib library in the desired project should be included and the following steps should be done:

Programming example for accessing V.E. variables in the PLC (VeExample1.pro)

VAR 
  VEInitialisationDone : BOOL;
  I : INT;
  pCHANNEL_WR : POINTER TO ARRAY [0..9] OF INT := 0;
  pGLOBAL_SWR : POINTER TO DINT := 0;
END_VAR 
(* Accessing VE variables in the SPS *) 
IF VEInitialisationDone = FALSE THEN
  VEInitialisationDone := VeInitialisation();
  IF VEInitialisationDone = TRUE THEN
    pCHANNEL_WR := VeSgn32(1,'CHANNEL_WR', SIZEOF(pCHANNEL_WR^));
    pGLOBAL_SWR := VeSgn16(1,'GLOBAL_SWR', 0);
  ELSE
    RETURN;
  END_IF
END_IF
(* Now there can be a direct access to the Ve variables. For testing:
- check the content of pChannel -> 801..802....
- to test the communication to system manager execute V.E.GLOBAL_SWR=20 to write the variable on CNC.
- afterwards that the pChannel variable should have the content 0. *)
IF pCHANNEL_WR <> 0 AND pGLOBAL_SWR <> 0 THEN (* reading access*)
IF pGLOBAL_SWR^ = 20 THEN (* reading access*)
  FOR I:=0 TO 9 BY 1 DO
    pCHANNEL_WR^[I] := 0; (* writing access*)
  END_FOR
ELSE
  FOR I:=0 TO 9 BY 1 DO
    pCHANNEL_WR^[I] := 800+I; (* writing access*)
  END_FOR
END_IF
pGLOBAL_SWR1^:=0; (* writing access*)

This PLC example shows, how the V.E variables could be used in the PLC by replicating the variable structures. Before accessing the pointers pVE[iChannelNr]^.addr or pVEGlob^.addr the HLI interface must be initialized (s. [HLI - Introduction]).

Programming example 2 VE variable access in PLC without TcCncUtilities.lib library (from version V2.10.1025.00 onwards)

TYPE VECTOR_T : 
  STRUCT 
    x : LREAL; 
    y : LREAL; 
    z : LREAL; 
  END_STRUCT 
END_TYPE
 
TYPE TARGET_POINT_T : 
  STRUCT 
    point : VECTOR_T; 
    valid : BOOL; 
  END_STRUCT 
END_TYPE 

TYPE TRAJEKTORIE_T : 
  STRUCT 
    nbr_points : DINT; 
    name : STRING(127); 
    points : ARRAY [0..9] OF TARGET_POINT_T; 
  END_STRUCT 
END_TYPE 

Definition of structures for the complete, entered V.E. memory block:

TYPE VE_GLOBAL: 
  STRUCT 
    var_global_1 : DINT; 
  END_STRUCT 
END_TYPE
 
TYPE VE_CHAN_1: 
  STRUCT 
    var_chan_1 : DINT; 
    array_chan_1 : ARRAY [0..19] OF INT; 
    name : STRING(127); 
    Trajektorie : TRAJEKTORIE_T; 
  END_STRUCT 
END_TYPE 

PLC program for the access on the V.E. variables:

PROGAM V_E 
  VAR 
    p_ve_chan_1 : POINTER TO VE_CHAN_1; 
END_VAR 

p_ve_chan_1 := ADR (pVe[1]^.addr^.AHLI_UNS32_Data); 
IF (p_ve_chan_1^.name = ‘‘) THEN 
  p_ve_chan_1^.trajektorie.name := ‚My Path!’ 
  p_ve_chan_1^.trajektorie.nbr_points := 2; 
  p_ve_chan_1^.trajektorie.points[0].valid := TRUE; 
  p_ve_chan_1^.trajektorie.points[0].point.x := 100.0; 
  p_ve_chan_1^.trajektorie.points[0].point.y := 200.0; 
  p_ve_chan_1^.trajektorie.points[0].point.z := 300.0; 
  p_ve_chan_1^.trajektorie.points[1].valid := TRUE; 
  p_ve_chan_1^.trajektorie.points[1].point.x := 200.0; 
  p_ve_chan_1^.trajektorie.points[1].point.y := 400.0; 
  p_ve_chan_1^.trajektorie.points[1].point.z := 600.0; 
END_IF;