Sdo Message Response Time - Omron CJ1W-ECT21 Operation Manual

4 EtherCAT Communications
 Tnj_refresh
The refresh time while the NJ-series CPU Unit exchanges the process data with the I/O bus can be
calculated with the following formula.
Tnj_refresh = 0.2 + (0.0007 x (IN data area size + OUT data area size))
Units of IN and OUT data area size are in channels (CH).
4-6-2

SDO Message Response Time

This section describes the method for calculating the SDO message response time of the EtherCAT
Slave Unit.
The message response time is the time from when the EtherCAT master sends the SDO data with the
mailbox until it receives the SDO response from the target EtherCAT Slave Unit.
Timing Chart for SDO Message Response Time
A timing chart for the SDO message response time is provided in the figure below. Use this timing chart
with the provided formula to determine the minimum SDO message response time.
Send requesting
Cycle of
process data
communication
Element
Ts_resp
*1
Tmaster
*1. The cycle time of the EtherCAT master is based on the assumption that the EtherCAT master cycle is the same
as the cycle of process data communication. Refer to the EtherCAT master manual about the relationship be-
tween these cycles.
Minimum SDO Message Response Time Formula
A formula is provided below to calculate the SDO message response time.
Minimum SDO Message Response Time = (((Ts_resp / Tmaster) + 1
*1. If Tmaster divides Ts_resp evenly, there is no need to add 1 in the formula.
*2. If 512 divides the data byte size of the message response evenly, there is no need to add 1.
The elements used in the minimum SDO message response time formula are described below. Units of
these elements are in ms.
4 - 12
SDO
EtherCAT master cycle
Tmaster
Ts_resp
EtherCAT Slave Unit message response time is 2 ms.
Cycle time of the EtherCAT master
(((data byte size of response message / 512) + 1
CJ-series EtherCAT Slave Units Operation Manual for NJ-series CPU Unit (W542)
Response data
preparation completed requesting SDO
*1
Tmaster *1
Description
*1
) x Tmaster) +
Receive
*2
) x Tmaster) + Tmaster