The DEFSUB Command [MLEPC]

The DEFSUB command can be used to define a subprogram that will later be called using the CALSUB command, or to define when subprograms should be output to the NC program, or to define the behavior of INDEX and COPY commands that are passed to the post-processor from the CAM system.

Subprogram Definition

The DEFSUB command is used to identify the beginning of the definition of a subprogram. A subprogram consists of: a DEFSUB command naming the subprogram; one or more part program instructions defining the body of the subprogram; and a terminating ENDSUB command. A subprogram is called by coding a CALSUB command with a matching subprogram identifier. This command is valid for all machine types.

\textbf{DEFSUB / ID}, \, \begin{pmatrix}\begin{array}{l} a \\ \mathtt{'}\mathit{name}\,\mathtt{'} \end{array}\end{pmatrix} \begin{bmatrix} ,\textbf{TYPE}, \begin{pmatrix}\begin{array}{l} \textbf{CNC} \\ \textbf{RANGE} \\ \textbf{INCLUD} \\ \textbf{CLDATA} \\ \textbf{SYSTEM} \end{array}\end{pmatrix} \end{bmatrix} \Big[ \big[ ,\textbf{OPTION} \,\big] ,b \, \Big]

The subprogram ID[1] can be identified by either a whole number value a, or by a quoted subprogram name.

Various subprogram types are supported:

  • CNC specifies a subprogram defined in a separate program element than the caller. The post-processor will output a subprogram containing the code generated from the DEFSUB-ENSUB block either immediately, or when called, or at the end of processing, depending on how the post-processor is configured. For each call, the post-processor will update the processing status based on the subprogram contents, and then will generate a call instruction to the subprogram.

  • RANGE specifies a subprogram defined as repeat range in the same program element as the caller. The post-processor will process the DEFSUB-ENDSUB contents at the first call, bounded by labels or sequence numbers. For each subsequent call, the post-processor will update the processing status based on the subprogram contents, and then will generate a call instruction to repeat the bounded code.

  • INCLUD specifies an emulated subprogram. The post-processor will save the contents of the subprogram, and then will post-process the saved CLDATA contents at each call.

  • CLDATA specifies to use preferably a CNC subprogram if supported, but if not then a RANGE repeat if supported, otherwise to emulate the subprogram (i.e., INCLUD).

  • SYSTEM specifies a controller resident subprogram. For each call, the post-processor will update the processing status based on the subprogram contents, and generate a call instruction to the controller resident subprogram. The subprogram itself is not output.

The couplet OPTION,b (keyword,string) specifies optional subprogram definition parameters, to be included on the subprogram definition NC block. This qualifier might not be valid for a specific NC controller and cannot be used when emulating subprograms.

A maximum of 500 subprograms can be defined in a program.

Subprogram Output

The following DEFSUB command forces immediate output of deferred subprogram definitions to the tape file (non deferred subprograms are not affected by this command).

\textbf{DEFSUB / NOW}

Normally, deferred subprograms are output at the end of the program. This command can be used to fine tune the placement of subprograms. Once the NOW keyword is coded, subsequent subprogram definitions will cause an error.

Index and Copy Behavior

The following DEFSUB command defines the behavior of INDEX and COPY commands that are passed to the post-processor from the CAM system.

\textbf{DEFSUB / INDEX} \begin{bmatrix} ,\textbf{TYPE}, \begin{pmatrix}\begin{array}{l} \textbf{ON} \\ \textbf{OFF} \\ \textbf{CNC} \\ \textbf{RANGE} \\ \textbf{INCLUD} \\ \textbf{CLDATA} \\ \textbf{SYSTEM} \end{array}\end{pmatrix} \end{bmatrix} \begin{bmatrix} ,\textbf{TRFORM}, \begin{pmatrix}\begin{array}{l} \textbf{OFF} \\ \textbf{INCR} \\ \textbf{LCS} \end{array}\end{pmatrix} \end{bmatrix}

TYPE,OFF inhibits INDEX and COPY processing in the post-processor. ON uses whatever choice was selected by the post-processor author in the CALSUB section questions. The remaining choices select how the copy will be generated: CNC causes the INDEX block to be saved and output as a subprogram, which is called once at the INDEX/NOMORE and again for each COPY. RANGE causes the INDEX block to be output bounded by labels or sequence numbers, which are called at each COPY. INCLUD expands the INDEX and COPY commands as they normally are done by the CAM system. CLDATA processes INDEX and COPY using the CNC or RANGE methods if available, otherwise expands them using the INCLUD method. SYSTEM is the same as CNC, except that the subprograms are not output to the NC code.

TRFORM,INCR outputs the INDEX block code in incremental so that COPY transformations can be done by prepositioning prior to each subprogram call; LCS outputs the INDEX block as-is, but outputs an LCS (local coordinate system) instruction prior to each subprogram call; and OFF (the default) outputs all codes “as-is” and assumes that the post-processor author or NC programmer have handled the transformation requirements.