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114 • Chapter 7 Application Programming DMC-3425
currently available. The command, DA?, will return the number of arrays which can be currently
defined. The DMC-3425 will have a maximum of 2000 array elements in up to 14 arrays. If an array
of 100 elements is defined, the command DM? will return the value 1900 and the command DA? will
return 13.
To list the contents of the variable space, use the interrogation command LV (List Variables). To list
the contents of array space, use the interrogation command, LA (List Arrays). To list the contents of
the Program space, use the interrogation command, LS (List). To list the application program labels
only, use the interrogation command, LL (List Labels).
Operands
An operand is a value in the controller. Below is a list of specific operands that are particularly
valuable for program debugging. To display an operand, the message command may be used. For
example, since the operand, _ED contains the last line of program execution, the command MG _ED
will display this line number.
_ED contains the last line of program execution. Useful to determine where program stopped.
_DL contains the number of available labels.
_UL contains the number of available variables.
_DA contains the number of available arrays.
_DM contains the number of available array elements.
_AB contains the state of the Abort Input
_LFx contains the state of the forward limit switch for the 'x' axis
_LRx contains the state of the reverse limit switch for the 'x' axis
Breakpoints and single stepping
The DMC-3425 has commands which allow active debugging of programs. The BK command is a
breakpoint which may be set to trigger upon execution of a specified line and thread. Upon the
program executing the specified line, the program or thread will pause at that line. The SL command
may then be used to single step through the program from that breakpoint. See the command reference
for more information on the BK and SL command.
EEPROM Memory Interrogation Operands
When the DMC-3425 powers up, any data stored in the EEPROM memory is automatically loaded for
use. This data includes the user program, variables and arrays, and controller parameters. If the
EEPROM has been corrupted, the corresponding memory sector is flagged as in error. The operand
_RS contains the state of the EEPROM as follows:
Bit Error Condition
Bit 3 Master reset error
Bit 2 Program checksum error
Bit 1 Parameter checksum error
Bit 0 Variable checksum error