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Message Service Transmission Delay Section 10-5
Example Calculation In this example, RECV(098) is used to receive 256 words of data from another
PLC. 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: 15 ms
• Remote node’s CPU execution mode: Normal
• Remote node’s CPU peripheral servicing time: Default (4%)
• Baud rate: 100Base-TX
Item Calculated value
CPU Bus Unit service cycle (local
node, 1)
10 ms
CPU Bus Unit service processing
time (local node, 1)
0.4 ms
Send processing (command) 0.550 ms ≅ 0.5 ms
Transmission delay (command) 0.0118 ms ≅ 0.1 ms
Receive processing (command) 0.704 ms ≅ 0.7 ms
CPU Bus Unit service cycle (remote
node)
15 ms
CPU Bus Unit service processing
time (remote node)
0.6 ms
Send processing (command) (256 × 0.002) + 0.550 = 1.062 ≅ 1.1 ms
Transmission delay (command) (256 × 0.0013) + 0.0118 = 0.3446 ≅ 0.3 ms
Receive processing (command) (256 × 0.003) + 0.704 = 1.472 ≅ 1.5 ms
CPU Bus Unit service cycle (local
node, 2)
10 ms
CPU Bus Unit service processing
time (local node, 2)
0.4 ms
Maximum transmission delay 10 + 0.4 + 0.5 + 0.1 + 0.7 + 15 + 0.6 + 1.1 +
0.3 + 1.5 + 10 + 0.4 = 40.6 ms