2. System Function 2.3.4. Setting the Synchronization Cycle Period The synchronization cycle period is a very important parameter in 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 first introduce the constitution of a synchronization period. The motion control program is scanned at the very beginning of a 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 10MC and all servos. The cycle period for execution of motion control program can refer to the value in D6501 with the unit: μs (microsecond). 1000 microseconds are 1ms (millisecond). The value is rounded up to an integer in the actual application. For example, the value in D6501 is 2567μs=2.5ms, in this case, we can regard 3ms as the time for program execution. It is about 0.5ms for communication between 10MC and a servo. We recommend that the value is rounded up to an integer in application. For example, 5 servos are configured in application.
And the communication ti me is 5*0.5ms=2.5ms. In this case, we can regard 3ms as the time for communication. Therefore, we can get the formulation: a synchronization time = an integer obtained by rounding up the value of D6501 + time for communication between 10MC and all servos +1 (time reserved for a program change). 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 time for execution of the program with D6501 is 1634ms and there are totally 5 servos in application. The reserved time for a program change is 1ms.
A synchronization cycle period= 2ms (obtained by rounding up D6501: 1634) + 3ms ((obtained by rounding up 5*0.5) +1ms (reserved for a program change) Note: The method above is 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 application development is completed. The synchronization cycle period can be set in the following red box and will go into effect after being downloaded. 2-22 DVP-MC operating manual