Omron SYSMAC 3G8F7-CLK13-E Operation Manual page 149

Communications Cycle Time
Calculation Example for
Wired Networks
Calculation Example for
Optical Ring Networks
with H-PCF Cable
D: Number of nodes that send messages during the
communications cycle
E: Total number of bytes in messages transmitted during the
communications cycle
F: Extra communications time for long-distance cable connections.
If L is the cable length in km, then F = 7 × L μs for H-PCF cable
and F = 5 × L μs for GI cable.
Communications conditions are as follows:
Type:
Transmission medium:
Baud rate:
Network parameters:
Max node address:
Polled nodes per comm cycle:
Event-frames per comm cycle: 35
Network configuration:
Total number of data link words: 8,000 words
Nodes that send messages:
Bytes in all messages sent:
In this example, A to E in the equation have the following values.
A: 8,000
B: 4
C: 8
D: 2
E: 4,024
The communications cycle time is thus as follows:
10 × 8,000 + 600 × 4 + 290 × 8 + 320 × 2 + 4 × 4,024 + 3,290 = 104,746 (μs)
≅ 105 (ms)
Communications conditions are as follows:
Type:
Transmission medium:
Transmission distance:
Baud rate:
Network parameters:
Max node address:
Polled nodes per comm cycle: 4
Event-frames per comm cycle: 35
Network configuration:
Total number of data link words: 8,000 words
Nodes that send messages:
Bytes in all messages sent:
In this example, A to E in the equation have the following values.
A: 8,000
B: 4
C: 8
D: 2
Wired
Twisted-pair cables
2 Mbps
Defaults
32
4
8 nodes
2 nodes
2,012 × 2 bytes
Optical Ring
H-PCF cable
8 km
2 Mbps (fixed)
Defaults
62
8 nodes
2 nodes
2,012 × 2 bytes
Section 8-2
129