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12 Communications Performance
NX-series EtherCAT Coupler Unit User’s Manual (W519)
12-1 Performance of Process Data Communications
12
12-1-1 I/O Response Times for Synchronous I/O Refreshing
Tmax-InTrans
This is the longest input transmission time of the EtherCAT Coupler Units in all of the EtherCAT
Slave Terminals in the same EtherCAT network.
The input data transmission time is the time that is required for the EtherCAT 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.
Use the following formula to find Tmax-InTrans.
Use the following formula to find T#n-InTrans.
Formula: Tmax-InTrans = Max(T#1-InTrans,
*1
T#2-InTrans,
*2
...T#n-InTrans
*3
)
*1. T#1-InTrans is the input data transmission time of the EtherCAT Coupler Unit in the EtherCAT Slave Ter-
minal with node address 1.
*2. T#2-InTrans is the input data transmission time of the EtherCAT Coupler Unit in the EtherCAT Slave Ter-
minal with node address 2.
*3. T#n-InTrans is the input data transmission time of the EtherCAT Coupler Unit in the EtherCAT Slave Ter-
minal with node address n. “#n” indicates the node address of the EtherCAT Slave Terminal. “n” is the ad-
dress.
“Max” indicates the maximum value in the parentheses.
Formula: T#n-InTrans = 9.22 × (Integer quotient of total byte size
*1
of the NX Unit input data ÷ 32)
*2
*1. This is the total byte size of the input data of the NX Units in the EtherCAT Slave Terminal.
*2. Round down the value that results from the calculation in parentheses to an integer. It is expressed as fol-
lows with a Microsoft Excel function:
ROUNDDOWN(Total_byte_size_of_all_NX_Unit_input_data/32,0)
+ 0.55 × (Remainder of quotient of total byte size*1 of the NX Unit input data ÷ 32)
*3
+ (0.34 × Number of NX Units with BOOL input data
*4
+ 3.41)
*5
+ 3.53 × Number of NX Units
*6
+ 0.014 × Total bytes size of NX Unit input data*1
+ 75.17
*3. This is the remainder. It is expressed as follows with a Microsoft Excel function:
MOD(Total_byte_size_of_all_NX_Unit_input_data/32,0)
*4. This is the number of NX Units for which there are I/O assignments to BOOL input data in the EtherCAT
Slave Terminal. For example, the NX-ID3317 meets this condition because it is an NX Unit that has BOOL
input data. However, the NX-ID4342 does not meet this condition because it is an NX Unit that has BYTE
input data.
*5. If there are no NX Units in the EtherCAT Slave Terminal that have I/O assignments to BOOL input data,
use 0 for the calculation in parentheses.
*6. This is the total number of NX Units in the EtherCAT Slave Terminal.
(Unit: μs)
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