Omron NJ101-10 Series, User Manual

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• NX701 CPU Units
Task to execute I/O refreshing
Process data communica-
tions cycle
Motion control
Primary periodic task Process data communications
cycle 1 Motion control 1
Priority-5 periodic task Process data communications
cycle 2 Motion control 2
• NX102 and NX1P2 CPU Units and NJ-series CPU Units
Task to execute I/O refreshing
Process data communica-
tions cycle
Motion control
Primary periodic task Process data communications
cycle Motion control

Restrictions for Multiple Communications Cycles
With an NX701 CPU Unit, you can perform process data communications separately in each task
period of the primary periodic task and the priority-5 periodic task. On the other hand, there is only
one EtherCAT network line. Therefore, some restrictions are placed on the process data communi-
cations in multiple communications cycles, as shown below.
• When the number of slaves controlled by the master increases, the process data communica-
tions cycles of both primary periodic task and priority-5 periodic task will get longer.
Consider the following countermeasures if the process data communications cycle for each task
exceeds the task period.
• If you want to maintain the number of the slaves, increase the task period of the task whose
process data communications cycle exceeds the task period.
• If you want to maintain the task period, decrease the number of the slaves.
• The process data communications for the primary periodic task is processed in priority over the
process data communications for the priority-5 periodic task. Therefore, the size of process data
for the priority-5 periodic task that can be processed becomes smaller than that for the primary
periodic task even if both tasks have the same task period.
Consider the following countermeasures if the process data communications cycle for the priori-
ty-5 periodic task exceeds the task period.
• If you want to maintain the process data size of priority-5 periodic task, increase the period of
the priority-5 periodic task.
• If you want to maintain the period of priority-5 periodic task, decrease the process data size of
the priority-5 periodic tasks that are assigned for the entire slaves.
6-1-3
Checking Validity of Process Data
When reading and writing the device variables and axes variables that input and output process data
with slaves, the validity of the process data must be checked.
When EtherCAT communications are not established, such as immediately after the power supply to
the CPU Unit is turned ON, the process data is invalid. Thus values become invalid for the device vari-
ables and axes variables that input and output the process data. If EtherCAT communications were
established previously, the device variables and axes variables retain the values updated while Ether-
CAT commutations were established then.
6 Process Data Communications and SDO Communications
6-6
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)