8-2
Section
Communications Cycle Time
117
Communications conditions are as follows:
Type:
Wired
Transmission medium:
Twisted-pair cables
Baud rate:
2 Mbps
Network parameters:
Defaults
Max node address:
32
Polled nodes per comm cycle: 4
Event-frames per comm cycle: 35
Network configuration:
8 nodes
Total number of data link words: 8,000 words
Nodes that send messages:
2 nodes
Bytes in all messages sent:
2,012
2 bytes
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 (
µ
s)
≅
105 (ms)
Communications conditions are as follows:
Type
Optical Ring
Transmission medium:
H-PCF cable
Transmission distance:
8 km
Baud rate:
2 Mbps (fixed)
Network parameters:
Defaults
Max node address:
62
Polled nodes per comm cycle: 4
Event-frames per comm cycle: 35
Network configuration:
8 nodes
Total number of data link words: 8,000 words
Nodes that send messages:
2 nodes
Bytes in all messages sent:
2,012
2 bytes
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
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 (
µ
s)
≅
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 (
µ
s)
≅
100 (ms)
Calculation Example for
Wired Networks
Calculation Example for
Optical Ring Networks
with H-PCF Cable
