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13 Communications Performance and Communications Load
NY-series Industrial Panel PC / Industrial Box PC Built-in EtherNet/IP Port User’s Manual (W563)
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The number of packets transferred each second is called the used bandwidth or PPS (packets per sec-
ond).
The PPS is calculated from the RPI and heartbeat as follows for each connection:
PPS used in a connection (pps) = (1,000
÷
RPI (ms)) + (1,000
÷
Heartbeat transmission period (ms))
Use the following equation to calculate the total number of packets transferred by each built-in Ether-
Net/IP port (Unit) in 1 second.
Built-in EtherNet/IP port’s total PPS = Total PPS of originator conne Total PPS of target connec-
tions*
* Connections set as target connections must be added, too.
The maximum number of packets that the built-in EtherNet/IP port for each series can transfer in 1 sec-
ond (called the allowed Unit bandwidth) is as follows, so set the connection below this maximum value.
•
NY-series Controller: 20,000 pps
Example:
Node 1 has both originator and target connections, with send RPI of 200 ms and 2 ms, and receive RPI
of 500 ms.
Node 2 has originator connections only, with receive RPIs of 200 ms, 2 ms, and 5 ms.
Node 3 has target connections only, with send RPIs of 5 ms and 1 ms.
Each node’s total PPS is calculated as follows:
•
Total PPS of node 1’s Unit
= 1000 / 200 ms + 1000 / 2 ms + 1000 / 500 ms (for data)
+ 1000 / 200 ms + 1000 / 100 ms + 1000 / 500 ms (for heartbeat)
= 524 pps
•
Total PPS of node 2’s Unit
= 1000 / 200ms + 1000 / 2 ms + 1000 / 5 ms (for data)
+ 1000 / 200ms + 1000 / 100 ms + 1000 / 100 ms (for heartbeat)
= 730 pps
•
Total PPS of node 3’s Unit
= 1000 / 5 ms + 1000 / 500 ms (for data)
+ 1000 / 100 ms + 1000 / 500 ms (for heartbeat)
= 214pps
All of the Units are within the allowed Unit bandwidth, so they can transfer data.
Requested Packet Interval (RPI) and Bandwidth Usage (PPS)
O: Originator
T: Target
HB: Heartbeat
O
O
O
O
T
T
T
T
RPI: 200 ms
HB: 200 ms
RPI: 2 ms
HB: 100 ms
RPI: 500 ms
HB: 500 ms
RPI: 5 ms
HB: 100 ms
Node 1
Node 2
Node 3
Summary of Contents for Sysmac NY512-1300
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