Omron SYSMAC CJ1W-EIP21 Operation Manual page 322

Message Service Transmission Delay
CPU Bus Unit Service
Processing Time (Remote
Node)
Note
Example Calculation
296
The following table shows the CPU Bus Unit service processing time, which
depends on the CPU Unit's CPU processing mode setting.
CPU execution mode
Normal Mode (See note.)
Priority peripheral servicing
Parallel processing with syn-
chronous memory access
Parallel processing with asyn-
chronous memory access
Note CJ2 CPU Units support only Normal Mode.
For details, refer to the CPU Unit's Operation Manual.
Depending on the actual operating environment, the transmission time may
be longer than the one calculated with the equations given here. The following
factors can cause longer transmission times: other traffic on the network, win-
dow sizes of network nodes, other traffic at the EtherNet/IP Unit or built-in Eth-
erNet/IP port itself (e.g., simultaneous tag data link communications), and the
system configuration.
In this example, SEND(090) is used to send 256 words of data between two
PLCs. The maximum transmission delay is calculated based on the following
operating conditions.
• Local node's CPU cycle time: 10 ms
• Local node's CPU execution mode: Normal
• Local node's CPU peripheral servicing time: Default (4%)
• Remote node's CPU cycle time: 5 ms
• Remote node's CPU execution mode: Normal
• Remote node's CPU peripheral servicing time: Default (4%)
• Baud rate: 100Base-TX
Item
CPU Bus Unit service cycle (local
node)
CPU Bus Unit service processing
time (local node)
Send processing
Transmission delay
Receive processing
CPU Bus Unit service cycle (remote
node)
CPU Bus Unit service processing
time (remote node)
Maximum transmission delay
Processing time details
Set peripheral servicing time
Default: 4% of CPU Unit cycle time
(10% for CJ2 CPU Units)
EtherNet/IP Unit or Time slice peripheral servicing
built-in EtherNet/IP execution time
port is given prior-
ity.
EtherNet/IP Unit or Set peripheral servicing time
built-in EtherNet/IP (Default: 4% of CPU Unit cycle
port is not given time)
priority.
Set peripheral servicing time
Default: 4% of CPU Unit cycle time
(10% for CJ2 CPU Units)
1 ms max.
Calculated value
10 ms
0.4 ms
(256 × 0.002) + 0.550 = 1.062 ≅ 1.1 ms
(256 × 0.0013) + 0.0118 = 0.3446 ≅ 0.3 ms
(256 × 0.003) + 0.704 = 1.472 ≅ 1.5 ms
5 ms
0.2 ms
10 + 0.4 + 1.1 + 0.3 + 1.5 + 5 + 0.2 = 18.5 ms
Section 10-5