Omron NX701-17 Series User Manual page 144

6 Process Data Communications and SDO Communications
NJ-series CPU Units
The calculation formula for the minimum message response time is given below.
Minimum message response time (ms) = Task period of the task that executes SDO communications
*1 The slave SDO processing time depends on the slaves. Refer to the manual for the slave.
*2 Round up the calculation result in parentheses to make an integer.
The following timing chart shows an example of the timing from an execution of the SDO communica-
tions instruction to the completion of the instruction execution, based on the performance model below.
Here, it is assumed that the program that executes the SDO communications instructions is assigned to
the primary periodic task.
Performance Model Example
Task period of primary periodic task [ms]
SDO response data size [byte]
Slave SDO processing time [ms]
Message response time [ms]
IO: I/O refreshing
UPG: User program execution
MC: Motion control
EtherCAT master processing
Line delay
Slave SDO processing
6-26
instruction
+ (Slave SDO processing time
*2
× Task period of primary periodic task
task)
+ (SDO response data size/256 bytes)
periodic task
Task period Task period
(1 ms) (1 ms)
IO UPG MC IO UPG MC
SDO
communications
instruction
executed.
Frame
sent.
Slave SDO processing time
SDO
request
received.
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)
*1
/Task period of primary periodic
*2
1
512
1.2
5
Task period Task period
(1 ms) (1 ms)
IO UPG MC IO UPG MC
SDO response
generation
completed.
× Task period of primary
Task period Task period
(1 ms) (1 ms)
IO UPG MC IO UPG MC
Execution of SDO
communications
instruction
completed.
EtherCAT master captures
SDO response data from slave:
256 bytes per frame.