Omron CS CJ1W-ETN21 Operation Manual page 218

Maximum Transmission Delays: Writing/Reading to CPU Unit
CPU Bus Unit Service
Processing Time
Transmission Processing
(Response)
Note
Example Calculations
194
For details, refer to the CPU Unit operation manual.
The processing time will be as follows, depending on the CPU processing
mode settings at the CPU Unit.
CPU execution mode
Normal Mode
Priority peripheral ser-
vicing
Parallel processing with
synchronous memory
access
Parallel processing with
asynchronous memory
access
For details, refer to the CPU Unit operation manual.
×
Number of words sent
The actual operating environment can cause transmission delays larger than
those calculated with the methods given here. Among the causes of longer
delays are the following: traffic on the network, window sizes at network
nodes, traffic through the Ethernet Unit (e.g., simultaneous socket servicing
and FTP server communications, etc.), and the system configuration.
The following example shows calculations for sending 256 words between two
PLC nodes using SEND(090). Calculations are shown in the following table.
Conditions
CPU cycle time: 10 ms
CPU execution mode: Normal
CPU uniform peripheral servicing time: Default (4%)
Baud rate: 100Base-TX
Item
Personal computer transmission pro-
cessing time
Transmission delay (command)
Reception processing time local
node) (command)
CPU Bus Unit service cycle (local
node)
CPU Bus Unit service processing
time (local node)
Transmission processing time (local
node) (response)
Transmission delay (command)
Personal computer reception pro-
cessing time
Maximum transmission delay time
Processing time considerations
4% of CPU Unit cycle time
Ethernet Unit is given Time slice peripheral servicing
priority. execution time
Ethernet Unit is not Set peripheral servicing time
given priority. (Default: 4% of CPU Unit cycle
time)
Set peripheral servicing time
(Default: 4% of CPU Unit cycle time)
1 ms max.
0.003 + 0.704 ms
---
256 × 0.0013 + 0.0118 = 0.3446 ≈ 0.3 ms
256 × 0.003 + 0.704 = 1.472 ≈ 1.5 ms
10 ms
0.4 ms
0.704 ms ≈ 0.7 ms
0.0118 ms ≈ 0.1 ms
---
Personal computer transmission/reception
processing time + 0.3 +1.5 + 10 + 0.4 + 0.7 +
0.1 = personal computer transmission/recep-
tion processing time + 13.0 ms
Section 7-5
Calculation