Calculation Method Of Load Factor - Panasonic AFP0HC32ET User Manual

Reference Information

7.1 Calculation Method of Load Factor

The communication load factor is a value obtained by dividing the number of communication
packets that an EtherNet/IP device sends/receives per second by a cyclic communication
allowable communication band (the number of packets that can be sent/received per second).
The load factors of FP0H and each target should be 100% or less.
 Load factor of FP0H
Unit communication load factor =
[Calculation 1] Calculating the number of communication packets sent/received per second
(pps)
Calculate from RPI. *1 pps = 1000 / RPI [ms]
When the COS (Change of State) trigger is set, it calculated as a communication
cycle RPI x 1/4.
[Example 1] For the connection that RPI is 1.0 [ms]
-
1000 / 1.0 = 1000pps
[Example 2] For the connection that RPI is 1.0 [ms] and the COS trigger is set
-
1000 / (1.0×(1/4)) = 4000 pps
[Calculation 2] Calculating the cyclic communication allowable communication band (pps)
Calculate from the data size per packet *2 and EDS information [Capacity] for
FP0H.
Data size per packet
2 to 510 bytes
511 to 1450 bytes
*2: Data size per packet
= Connection transmission/reception data size = Raw data size + 32-bit
header size *3
*3. The 32-bit header size varies according to the connected target devices.
It is automatically given when calculating the load factor.
[Example 3] When the connection transmission raw data size is 256 bytes without
32-bit header
(256 + 2) = 258 bytes ≤ 510 -> 5000 pps
[Example 4] When the connection transmission raw data size is 512 bytes with 32-
-
bit header
(512 + 6) = 518 bytes ≥ 511 -> 2500 pps
7-2
Number of communication packets
sent/received per second (pps)
Cyclic communication allowable
communication band (pps)
Without 32-bit header
With 32-bit header
EDS information for FP0H [Capacity]
5000 pps
2500 pps
2 bytes
6 bytes
X 100%