CJ1W-EIP21 Omron, CJ1W-EIP21 Datasheet - Page 291

• Manufacturer Part Number: CJ1W-EIP21
• Description: Ethernet I/P Module
• Manufacturer: Omron

Specifications of CJ1W-EIP21

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Packet Interval (RPI)
and Bandwidth Usage
(PPS)
Communications System
In a tag data link, the number of packets transferred each second is called the
bandwidth used or PPS (packets per second).
The PPS is calculated from the RPI and heartbeat as follows for each connec-
tion:
The following equation is used to calculate the total number of packets trans-
ferred by each EtherNet/IP Unit or built-in EtherNet/IP port in 1 second.
The maximum number of packets that the Unit can transfer in 1 second
(called the allowed Unit bandwidth) is 6,000 pps (CJ2M-EIP21: 3,000 pps), so
set the connection below this maximum value.
Example
Node 1 has both originator and target connections, with send RPI of 200 ms
and 2 ms, and receive RPI of 1 ms.
Node 2 has originator connections only, with receive RPI of 200 ms, 2 ms, and
5 ms.
Node 3 has target connections only, with send RPI of 5 ms and 1 ms.
Each node’s total PPS is calculated as follows.
All of the Units are within the allowed Unit bandwidth of 6,000 pps (CJ2M-
EIP21: 3,000 pps), so they can transfer data.
O
PPS used in a connection (pps)
Unit’s total PPS = Total PPS of originator connections
• Total PPS of node 1 Unit
• Total PPS of node 2 Unit
• Total PPS of node 3 Unit
Node 2
RPI: 200 ms
HB: 200 ms
Note Connections set as target connections must be added, too.
= 1,000 / 200 ms + 1,000 / 2 ms + 1,000 / 1 ms (for data)
= 1,530 pps
= 1,000 / 200 ms + 1,000 / 2 ms + 1,000 / 5 ms (for data)
= 730 pps
= 1,000 / 5 ms + 1,000 / 1 ms (for data)
= 1,220 pps
+1,000 / 200 ms + 1,000 / 100 ms + 1,000 / 100 ms (for heartbeat)
+1,000 / 200 ms + 1,000 / 100 ms + 1,000 / 100 ms (for heartbeat)
+1,000 / 100 ms + 1,000 / 100 ms (for heartbeat)
= (1,000 ÷ RPI (ms)) + (1,000 ÷ Heartbeat transmission period (ms))
O
O
T
+ Total PPS of target connections (See note.)
RPI: 2 ms
HB: 100 ms
RPI:5ms
HB:100ms
T
Node 1
O
T
RPI: 1 ms
HB: 100 ms
Node 3
T
Section 10-1
O: Originator
T: Target
HB: Heartbeat
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