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DMC-1700/1800 Chapter 7 Application Programming • 139
PR 1000 Define relative distance
BGX Begin motion
AMX After motion done
WT 10 Wait 10 msec
JP #LOOP2,@IN[2]=1 Repeat motion unless Input 2 is low
HX Halt all tasks
The program above is executed with the instruction XQ #TASK2,0 which designates TASK2 as the main thread (ie.
Thread 0). #TASK1 is executed within TASK2.
Debugging Programs
The DMC-1700/1800 provides commands and operands which are useful in debugging application programs.
These commands include interrogation commands to monitor program execution, determine the state of the
controller and the contents of the controllers program, array, and variable space. Operands also contain important
status information which can help to debug a program.
Trace Commands
The trace command causes the controller to send each line in a program to the host computer immediately prior to
execution. Tracing is enabled with the command, TR1. TR0 turns the trace function off. Note: When the trace
function is enabled, the line numbers as well as the command line will be displayed as each command line is
executed.
Data which is output from the controller is stored in an output FIFO buffer. The output FIFO buffer can store up to
512 characters of information. In normal operation, the controller places output into the FIFO buffer. The software
on the host computer monitors this buffer and reads information as needed. When the trace mode is enabled, the
controller will send information to the FIFO buffer at a very high rate. In general, the FIFO will become full since
the software is unable to read the information fast enough. When the FIFO becomes full, program execution will be
delayed until it is cleared. If the user wants to avoid this delay, the command CW,1 can be given. This command
causes the controller to throw away the data which can not be placed into the FIFO. In this case, the controller does
not delay program execution.
Error Code Command
When there is a program error, the DMC-1700/1800 halts the program execution at the point where the error occurs.
To display the last line number of program execution, issue the command, MG _ED.
The user can obtain information about the type of error condition that occurred by using the command, TC1. This
command reports back a number and a text message which describes the error condition. The command, TC0 or
TC, will return the error code without the text message. For more information about the command, TC, see the
Command Reference.
Stop Code Command
The status of motion for each axis can be determined by using the stop code command, SC. This can be useful when
motion on an axis has stopped unexpectedly. The command SC will return a number representing the motion status.
See the command reference for further information.
RAM Memory Interrogation Commands
For debugging the status of the program memory, array memory, or variable memory, the DMC-1700/1800 has
several useful commands. The command, DM ?, will return the number of array elements currently available. The
command, DA ?, will return the number of arrays which can be currently defined. For example, a standard DMC-
1710 or DMC-1810 will have a maximum of 8000 array elements in up to 30 arrays. If an array of 100 elements is
defined, the command DM ? will return the value 7900 and the command DA ? will return 29.
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