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12 Communications Performance
NX-series EtherCAT Coupler Unit User’s Manual (W519)
12-1
P
e
rform
ance o
f Proces
s Dat
a Com
m
u
n
icat
ion
s
12
12-
1-2
I/O R
espon
se T
ime
s for
Fr
ee-Run
Refreshing
The maximum and minimum values of the I/O response time are calculated as follows: The minimum
value occurs when the time lags that are shown in the above figure do not occur.
The elements in the formulas are as follows: “#n” indicates the node address of the EtherCAT Slave
Terminal. “n” is the address.
• Tcycle: Task period of the primary periodic task in the CPU Unit
• Edelay: Transmission delay time of the EtherCAT master
• Etxj: Transmission jitter of the EtherCAT master
• T#n-InTrans: Input data transmission time for EtherCAT Coupler Unit
• T#n-OutTrans: Output data transmission time for EtherCAT Coupler Unit
• T#n-Free_I/OCycle: Refresh cycle of NX but in EtherCAT Slave Terminal in Free-Run Mode.
• Tnx-InProc: Input data processing time of the NX Unit
• Tnx-OutProc: Output data processing time of the NX Unit
• Tnx-Indelay: Input delay time of the NX Unit
• Tnx-Outdelay: Output delay time of the NX Unit
This section defines the elements and describes the calculation methods.
 Tcycle
This is the time that is set for the task period of the primary periodic task in the CPU Unit
 Edelay
This is the transmission delay time of the EtherCAT master. Refer to Definitions of Formula Ele-
ments and Calculation Methods on page 12-4 in 12-1-1 I/O Response Times for Synchronous I/O
Refreshing on page 12-2 for the formula for Edelay.
 Etxj
This is the transmission jitter of the EtherCAT master.
The value is 100
μ
s.
 T#n-InTrans
This is the input data transmission time of the EtherCAT Coupler Unit in the EtherCAT Slave Termi-
nal with node address n. The input data transmission time is the time that is required for the Ether-
CAT Coupler Unit to read all of the input data for all of the NX Units. After all of the input data is read,
the EtherCAT Coupler Unit is ready to send the data to the EtherCAT communications path.
Refer to Definitions of Formula Elements and Calculation Methods on page 12-4 in 12-1-1 I/O
Response Times for Synchronous I/O Refreshing on page 12-2 for the formula for T#n-InTrans. Use
the formula for T#n-InTrans in the description of Tmax-InTrans in the referenced section.
Formula: Maximum I/O response time = Tcycle
×
2 + Etxj + T#n-Free_I/OCycle
×
2
+ T#n-I T#n-Ou Tnx-InProc
×
2
+ Tnx-OutProc
×
2 + Tnx-I Tnx-Outdelay
Formula: Minimum I/O response time = Etxj + T#n-I T#n-OutTrans
+ Tnx- Tnx-O Tnx-I Tnx-Outdelay
Definition of Formula Elements and Calculation Methods