Cyclical Channel Interface

The channel interface is responsible for the cyclic data exchange between the PLC and the NCI.

	The NC input/output variable names can sometimes differ from the PLC input/output variable names. However, this is not really significant. This description relates to the naming in the PLC.

From the NCI to the PLC (150 bytes)

TYPE NciChannelToPlc :
STRUCT
    nJobNo             : DWORD;
    nFastMFuncMask     : ARRAY[1..5] OF DWORD; (* Mask to evaluate fast M-unctions *)
    nHskMFuncNo        : WORD; (* evaluate M-function with handshake *)
    nHskMFuncReq       : WORD;
    nHFuncValue        : DINT;
    nSpindleRpm        : WORD;
    nTool              : WORD;
    nReserved1         : ARRAY[37..132] OF BYTE;
    nLoadedProg        : DWORD; (* loaded program number if exist *)
    nItpMode           : WORD; (* Interpreter mode *)
    nItpState          : WORD; (* Interpreter status *)
    nItpErrCode        : WORD; (* Interpreter-Channel Error Code *)
    nReserved2         : ARRAY[143..150] OF BYTE;
END_STRUCT
END_TYPE

Variable name	Data type	Description
nJobNo	DWORD	Job number
nFastMFuncMask	ARRAY OF DWORD	Bit mask for evaluation of the fast M-functions
nHskMFuncNo	WORD	Number of synchronous M-function present (M-function with handshake)
nHskMFuncReq	WORD	Flag indicating that a synchronous M-function is present 0: no synchronous M-function is present 1: a synchronous M-function is present
nHFuncValue	DINT	Value of the auxiliary function
nSpindleRpm	WORD	Spindle rotation speed
nTool	WORD	Tool number
nLoadedProg	DWORD	Name of the NC program presently being executed. If the name is not a DWORD, this value is 0.
nItpOpMode	WORD	Bit mask that indicates execution in interpreter mode.
nItpState	WORD	Interpreter state
nItpErrorCode	WORD	Error code of the interpreter channel

The above structure contains some reserved areas. Some of these areas are used in newer TwinCAT versions. On the PLC side the structure was not renamed, so that relevant data can be read with the PLC function.

NCI to PLC (structure from NC perspective)

Variable name	Data type	Description
mJobNr		see table above nJobNo
mDWORD		see table above nFastMFuncMask
sHandshake.nFunc		see table above nHskMFuncNo
sHandshake.nRequested		see table above nHskMFuncReq
sHandshake.nHFuncValue		see table above nHFuncValue
sHandshake.nSpindelRPM		see table above nSpindleRpm
sHandshake.nTool		see table above nTool
nChnState	DWORD
nChnState.bIsEStopRequested	Bit 8 (zero based)	Indicates that an ItpEStop was called, without checking whether the axes are already at standstill.
nChnState.bIsFeedFromBackupList	Bit 10 (zero based)	For retracing the current entries from the interpreter backup list are sent
nChnState.bIsMovingBackward	Bit 11 (zero based)	Indicates that the current motion is a backward movement (from TC 2.11 Build 1550)
nParams	Array of DWORD	Data of the freely configurable channel interface (see ItpSetCyclicUDintOffsets)
fParams	Array of LREAL	Data of the freely configurable channel interface (see ItpSetCyclicLrealOffsets)
mProgNr		see table above nLoadedProg
mItpOpMode		see table above nItpOpMode
mItpOpState		see table above nItpState
mErrorCode		see table above nItpErrorCode
nChnId	WORD	Channel ID
nGrpId	WORD	Group ID
nItfVersion	WORD	Version of this cyclic channel interface

From PLC to NCI (150 bytes)

TYPE NciChannelFromPlc :
STRUCT
    nSkipLine          : WORD; (* Mask to skip lines *)
    nItpMode           : WORD;
    nMFuncGranted      : WORD; (* granted signal of the M-function *)
    nReserved1         : ARRAY[7..14] OF BYTE;
    nChaAxesOvr        : DWORD; (* Channel override in percent * 100 *)
    nChaSpindleOvr     : DWORD;
    nReserved2         : ARRAY[23..150] OF BYTE;
END_STRUCT
END_TYPE

Variable name	Data type	Description
nSkipLine	WORD	Bit mask with which block skipping of the NCI is parameterized from the PLC.
nItpMode	WORD	Bit mask with which the interpreter execution mode can be altered. This is, for instance, required if the interpreter is to operate in single block mode.
nMFuncGranted	WORD	Flag with which an M-function of type 'Handshake' is acknowledged 0: not acknowledged 1: acknowledgement
nChaAxesOvr	DWORD	Channel override for the axes from 0...1000000 (corresponds to 0 - 100%)
nChaSpindleOvr	DWORD	Channel override for the spindle from 0...1000000 (corresponds to 0 - 100%)