129
Communications Cycle Time
Section 8-2
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
μ
s for H-PCF cable
and F = 5
×
L
μ
s for GI cable.
Calculation Example for
Wired Networks
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)
Calculation Example for
Optical Ring Networks
with H-PCF Cable
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
Summary of Contents for SYSMAC 3G8F7-CLK12-EV1
Page 2: ......
Page 4: ...iv ...
Page 20: ...xx Conformance to EC Directives 6 ...
Page 48: ...28 Applications Precautions Section 1 4 Example CX Programmer Response Timeout Setting ...
Page 68: ...48 Backup Power Supply Wiring Optical Ring Systems Only Section 2 4 ...
Page 74: ...54 Using the C Library Section 3 2 ...
Page 110: ...90 Changing the Data Link Tables with Active Data Links Section 5 5 ...
Page 187: ......