DMC-1500 Chapter 7 Application Programming • 87
The operand _DM returns the number of available array elements.
Debugging Example:
The following program has an error. It attempts to specify a relative movement while the X-axis is
already in motion. When the program is executed, the controller stops at line 003. The user can then
query the controller using the command, TC1. The controller responds with the corresponding
explanation:
Instruction Interpretation
:ED Edit Mode
000 #A Program Label
001 PR1000 Position Relative 1000
002 BGX Begin
003 PR5000 Position Relative 5000
004 EN End
<cntrl> Q Quit Edit Mode
:XQ #A Execute #A
?003 PR5000 Error on Line 3
:TC1 Tell Error Code
?7 Command not valid
while running.
Command not valid while running
:ED 3 Edit Line 3
003 AMX;PR5000;BGX Add After Motion Done
<cntrl> Q Quit Edit Mode
:XQ #A Execute #A
Program Flow Commands
The DMC-1500 provides instructions to control program flow. The DMC-1500 program sequencer
normally executes program instructions sequentially. The program flow can be altered with the use of
event triggers, trippoints, and conditional jump statements.
Event Triggers & Trippoints
To function independently from the host computer, the DMC-1500 can be programmed to make
decisions based on the occurrence of an event. Such events include waiting for motion to be complete,
waiting for a specified amount of time to elapse, or waiting for an input to change logic levels.
The DMC-1500 provides several event triggers that cause the program sequencer to halt until the
specified event occurs. Normally, a program is automatically executed sequentially one line at a time.
When an event trigger instruction is decoded, however, the actual program sequence is halted. The
program sequence does not continue until the event trigger is "tripped". For example, the motion
complete trigger can be used to separate two move sequences in a program. The commands for the
second move sequence will not be executed until the motion is complete on the first motion sequence.
In this way, the DMC-1500 can make decisions based on its own status or external events without
intervention from a host computer.
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