Inactive Data Links - Omron SYSMAC 3G8F7-CLK13-E Operation Manual

Communications Cycle Time
8-2-2

Inactive Data Links

Calculation Example for
Wired Networks
130
E: 4,024
F: 7 × 8
The communications cycle time for Token Ring Mode is thus as follows:
9.1 × 8,000 + 1,740 × 4 + 960 × 8 + 1,100 × 2 + 4 × 4,024 + 2 × 7 × 8 +
4,800 = 110,648 (μs) ≅ 111 (ms)
The communications cycle time for Token Bus Mode is thus as follows:
9.1 × 8,000 + 1,300 × 4 + 290 × 8 + 320 × 2 + 4 × 4,024 + 2 × 7 × 8 + 2,290
= 99,458 (μs) ≅ 100 (ms)
The following equations are used to calculate the communications cycle time
when the data links are inactive. (The communications cycle time will vary
somewhat depending on the baud rate and the conditions at that particular
time.)
Wired Networks
Baud rate
2 Mbps 600 × B + 110 × C + 320 × D + 4 × E + 2,290 (μs)
1 Mbps 1,150 × B + 150 × C + 360 × D + 8 × E + 2,690 (μs)
500 Kbps 2,260 × B + 230 × C + 440 × D + 16 × E + 3,490 (μs)
Optical Ring Networks
Baud rate
2 Mbps Token Ring Mode
1,740 × B + 450 × C +1,100 × D + 4 × E + 2 × F + 3,000 (μs)
(fixed)
Token Bus Mode
1,300 × B + 110 × C + 320 × D + 4 × E + 2 × F + 1,800 (μs)
Note B: Number of polled nodes per communications cycle
(value specified in the network parameter)
C: Number of nodes connected to network
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 connec-
tions.
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:
Nodes that send messages:
Bytes in all messages sent:
Equation
Equation
Wired
Twisted-pair cables
2 Mbps
Defaults
32
4
8 nodes
2 nodes
2,012 × 2 bytes
Section 8-2