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You can use the following formula for the calculation by a formula. The value that is found in the
formula is a roughly-estimated value.
Transmission delay time (μs) =
1.24
[μs] x Number of EtherCAT 0.082 [μs] x EtherCAT
frame length [bytes] + 0.01 [μs] x Total cable length [m]
*1.
For project unit version 1.40 or later, this value is 1.60.
The parameters necessary for calculation are described below.
Parameter
Description
Number of EtherCAT
Slaves
This is the number of all of the EtherCAT slaves in the same EtherCAT net-
work. An EtherCAT Slave Terminal is counted as one EtherCAT slave.
EtherCAT Frame Length
in Bytes
The EtherCAT frame length is the data byte size that is calculated under the
following conditions for the EtherCAT slaves in the same EtherCAT network
and for which I/O is refreshed in the primary periodic task.
•
If the total data size is less than 64 bytes, use 64 bytes in the calculation.
•
For EtherCAT slaves that have both input and output data, use the larger
of the input data size and output data size.
For example, the EtherCAT frame length in bytes for the following configura-
tion is as given below.
Configuration Example
•
Two OMRON GX-series EtherCAT slaves:
Data size of 20 bytes/slave
•
One EtherCAT Slave Terminal:
Input data size of 50 bytes and output data size of 30 bytes
EtherCAT frame length = 20 bytes + 20 bytes + 50 bytes = 90 bytes
Total Cable Length
This is the total cable length, including the cable between the EtherCAT mas-
ter and a slave and cables between slaves.
Transmission Jitter
The value of transmission jitter depends on the CPU Unit.
CPU Unit
Transmission jitter
NX701
10 μs
NX102
NX1P2
NJ-series
100 μs
Slave Input Response Time
This is the time from when a slave reads input information from output devices until the slave trans-
mits a frame as a process data on the EtherCAT communications. This is the time required for in-
ternal processing that is specific to each slave. Refer to relevant manuals for each slave.
Slave Output Response Time
This is the time from when a slave receives a frame as a process data on the EtherCAT communi-
cations until the slave outputs the frame as output data to external output devices. This is the time
required for internal processing that is specific to each slave. Refer to relevant manuals for each
slave.
6 Process Data Communications and SDO Communications
6-13
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)
6-1 Process Data Communications (PDO Communications)
6
6-1-4
System Response T
ime in Process Data Communications
Summary of Contents for NJ101-10 Series
Page 10: ...Manual Structure 8 NJ NX series CPU Unit Built in EtherCAT Port User s Manual W505...
Page 80: ...3 EtherCAT Communications 3 12 NJ NX series CPU Unit Built in EtherCAT Port User s Manual W505...
Page 236: ...9 Troubleshooting 9 38 NJ NX series CPU Unit Built in EtherCAT Port User s Manual W505...
Page 274: ...Appendices A 38 NJ NX series CPU Unit Built in EtherCAT Port User s Manual W505...
Page 275: ...I Index I 1 NJ NX series CPU Unit Built in EtherCAT Port User s Manual W505 I...
Page 279: ......