Delta Electronics DVP15MC11T, Operation Manual

Page: 70 / 601

Chapter 7 Introduction of Axis Parameters
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7.4 Synchronization Cycle Period Setting
The synchronization cycle is a very important parameter for the bus motion control. If the synchronization
period is not set properly, the servo may display AL303/AL302/AL301 fault alarm in communication or the
servo could not run normally.
Let’s introduce the constitution of the synchronization period first.
The motion control program is scanned at the very beginning of the synchronization period, and then the
control messages got through calculation are sent to all axes. So we can regard the synchronization period
as the time for execution of motion control program plus the time for communication between DVP15MC and
all servos.
The time for execution of motion control program is the maximum execution time of motion event tasks with
the
unit: μs (microsecond)
which can be viewed by double clicks on Task on the CANopen Builder software
interface. 1000
μs
(microseconds) are 1ms (millisecond).
The value is rounded up to an integer in the actual application. For example, the maximum time for program
execution is 2567μs=2.5ms, in this case, we can regard 3ms as the time for program execution.
It is about 0.5ms for the communication between DVP15MC and a servo.
We recommend that the value is rounded up to an integer in application. For example, 5 servos are
configured in an application. And the communication time is 5*0.5ms=2.5ms. In this case, we can regard
3ms as the time for communication.
Therefore, we can get the formula: a synchronization time (ms) = an integer obtained by rounding up the
value of maximum program execution time (ms) + time for the communication between DVP15MC11T and
all servos (ms) +1 (time reserved for a program change) (ms).
If the running time of the program is increased too much after the program changes, the preset
synchronization time will not fit any more. So the reserved time should be set to 1~2ms.
For example, the maximum program execution time is 1634
μs
and there are totally 5 servos in the
application. The reserved time for a program change is 1ms.
A synchronization cycle period= 2ms (obtained by rounding up the maximum program execution time,
1634
μs
) + 3ms (obtained by rounding up 5*0.5) +1ms (reserved for a program change)=6ms
Note:
The above method is used for getting an estimated time, which is suitable for most applications. If you need
a more precise synchronization cycle period, the actual time can be recalculated by omitting the reserved
time after the application development is completed.
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