22
Allocating Network Bandwidth Usage and Calculating the Best EPI
Section 2-2
If using both safety and standard I/O communications:
Input the total network bandwidth used for safety and standard connec-
tions as 90% or less, e.g., 40% for safety connections and 30% for stan-
dard connections.
Safety and standard I/O communications will use the bandwidth based on
the rates specified here.
4.
Click the
Calculate
Button.
5.
The best average EPI of all the connections in the safety I/O communica-
tions and the optimum Master communications cycle time in the standard
I/O communications will be displayed for each baud rate.
6.
Perform the following trial calculation.
• When using safety I/O communications only
Increase the network bandwidth for safety connections to 90%. If the
desired best EPI for each safety connection cannot be calculated, try
increasing the EPI for connections that need faster speeds (EPI settings,
step 9 as described later).
• When using a mixture of safety and standard I/O communications:
Try changing the network bandwidth usage rate and calculating the EPI,
as described below.
• Increase the usage rate for safety connections to shorten the EPI for
safety I/O communications and lengthen the communications cycle time
for standard I/O communications.
•
Conversely, increase the usage rate for standard communications to
shorten the cycle time for standard I/O communications and increase the
EPI for safety I/O communications.
7.
Check the Safety Network Controller cycle time.
Next, check that the cycle times calculated in the previous steps are longer
than the Safety Network Controller cycle time. If they are shorter, the Safe-
ty Network Controller cycle time will be the minimum that can be set for the
EPI. The Safety Network Controller cycle time can be checked offline after
creating the program, under
Cycle Time
on the Mode/Cycle Time Tab in
the Edit Device Parameters Dialog Box. Refer to
5-6 Setting the Operating
Mode and Confirming the Cycle Time
.
Summary of Contents for DeviceNet Safety
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