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Message Delay Times Section 8-4
Reception Processing
Commands: 1.3 ms
Responses: Number of words transferred
× 0.00075 ms + 2 ms
The I/O response time can increase due to noise or restrictions on the number
of frames that can be transmitted while the data link is operating.
Example
In this example, the maximum transmission delay is calculated for an instruc-
tion receiving 256 words of data in a system with 32 nodes. Network specifics
are detailed below:
Baud rate: 2 Mbps
Max. node address: 32
Number of nodes: 32
Number of polled nodes per comm cycle: 4
Source node execution: Synchronous
Destination node execution: Asynchronous
Number of words: 256
Data link: Inactive
Note This communications cycle time is calculated assuming that there is no node
that transmits event frames before the RECV command is sent.
Link Unit servicing (source node) × 2 PLC cycle time (source node) × 2
Link service processing (source node) × 21 ms × 2 = 2 ms
Transmission processing (command) 2 ms
Communications cycle × 2 (See note.) (600 × 4 + 110 × 32 + 320 × 0 + 4 ×
0 + 2,290) × 2 = 8,210 µs × 2 ≅
16.4 ms
Transmission delay (command) 0.112 ≅ 0.1 ms
Reception processing (command) 1.3 ms
Link servicing interval (destination node) As required by Programming
Device (destination node)
Link service processing (destination node) 1 ms
Transmission processing (response) 0.00075 × 256 + 2 = 2.192 ≅
2.2 ms
Transmission delay (response) 0.008 × 256 + 0.112 = 2.16 ≅
2.2 ms
Reception processing (response) 0.00075 × 256 + 2 = 2.192 ≅
2.2 ms
Total (max. transmission delay) PLC cycle time (source node) ×
2 + Peripheral servicing time
(destination node) + 29.4 ms