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130
Communications Cycle Time
Section 8-2
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)
8-2-2
Inactive Data Links
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
Optical Ring Networks
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
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
Nodes that send messages: 2
nodes
Bytes in all messages sent:
2,012
×
2 bytes
Baud rate
Equation
2 Mbps
600
×
B + 110
×
C + 320
×
D + 4
×
E + 2,290 (
μ
s)
1 Mbps
1,150
×
B + 150
×
C + 360
×
D + 8
×
E + 2,690 (
μ
s)
500 Kbps
2,260
×
B + 230
×
C + 440
×
D + 16
×
E + 3,490 (
μ
s)
Baud rate
Equation
2 Mbps
(fixed)
Token Ring Mode
1,740
×
B + 450
×
C +1,100
×
D + 4
×
E + 2
×
F + 3,000 (
μ
s)
Token Bus Mode
1,300
×
B + 110
×
C + 320
×
D + 4
×
E + 2
×
F + 1,800 (
μ
s)
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: ......