Omron DeviceNet CV Series Operation Manual page 322

Remote I/O Communications Characteristics
PLC
Master Unit processing
Input
Output
Note
7-1-2 Communications Cycle Time and Refresh Time
Communications Cycle
Time
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Maximum I/O Response Time
The maximum I/O response time occurs with the I/O timing shown in the fol-
lowing diagram.
Program execution
T
PLC
T : The Input Slave's ON (OFF) delay
IN
T : The Output Slave's ON (OFF) delay
OUT
T : The communications cycle time for the total Network (See page 305.)
RM
T : The PLC's cycle time
PLC
T : The PLC's DeviceNet Unit refresh time (See page 307.)
RF
The maximum I/O response time (T
+ 2 × T
T = T
MAX IN RM
1. Refer to SECTION 4 General-purpose Slaves, SECTION 5 Environment-
resistive and Waterproof Slaves, and SECTION 6 Special I/O Slave Units
Specifications for details on Input and Output Slaves' delay times.
2. Refer to Refresh Time on page 307 and the PLC's Operation Manual for
details on the PLC's peripheral servicing cycle time.
The communications cycle time, communications time for each Slave, and
refresh time are explained in this section. All of these are necessary for calcu-
lating the time required for various processes in a DeviceNet Network.
The communications cycle time is the time from the completion of a Slave's
remote I/O communications processing until remote I/O communications with
the same Slave are processed again. The communications cycle time is used
to calculate the maximum I/O response time.
The communications cycle time depends on the number of Masters on the
Network and on whether or not message communications are being per-
formed. The following equations are valid when there is only one Master Unit.
For details on cycle time equations for multiple Master Units, refer to
page 307 .
One Master in Network
The following equations show the communications cycle time (T
there is only one Master in the Network. Even if the equation result is less
than 2 ms, the minimum communications cycle time (T
Program execution Program execution
T
PLC
) is the total of the following terms:
MAX
+ 2 × T
+ T + T
PLC RF OUT
Section 7-1
) when
RM
) is 2 ms.
RM
305