Yamaha ERCX Series, User Manual

Page: 119 / 260

8-
5
8
ROBOT LANGUAGE
8-3 Program Function
8-3 Program Function
8-3-1 Multi-task function
A multi-task function allows simultaneous executing two or more programs (tasks). The ERCX con-
troller can execute a maximum of 4 programs at the same time.
Since the multi-task function simultaneously executes two or more programs, the following process-
ing can be performed.
■
Other processing can be performed during robot movement.
For example, a general-purpose output can be turned on or off while a robot movement com-
mand such as MOVA or MOVI statement is being executed. This reduces the cycle time.
A multi-task program can be written by the same method as normal programs. A TON statement used
as the task start command is written into the main program and the subtask program is registered as
another program number. When the TON command is processed during the program execution, the
subtask starts to perform multiple tasks. The subtask will end when its last step has been executed or
the TOFF command is issued.
Each task and data have the following relation.
Point variables P in a task are independent of those in other tasks.
Point data, general-purpose I/O and memory I/O are shared with each task.
c
CAUTION
In addition to the tasks (up to 4 tasks) specified by the user, the system task starts inside the controller, so a
maximum of 5 tasks are executed.
In general, the multi-task is defined as a function that simultaneously executes two or more programs (tasks).
Strictly speaking, if the CPU is one unit, it executes two or more programs (tasks) while switching between them
in an extremely short time almost as if they were being simultaneously executed. The ERCX controller uses this
multi-task function to perform multiple tasks while switching the programs within a very short time (5ms
maximum). Because of this, if 4 tasks are executed with this function, there is a maximum time of 20ms during
which no processing is performed on one task. So the user must take this time into account when designing a
system having multi-task functions.