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Communications Cycle Time
Section 8-2
The number of bytes in each message differs according to the instruction
being issued.
Calculation Example
Communications conditions are as follows:
Transmission medium:
Twisted-pair cable
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)
8-2-2
Inactive Data Links
The following equations are used to calculate a communications cycle time
when the data link is inactive.
Wired Systems
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
Instruction
When sent
When received
SEND
Number of words to be sent
×
2 +
18
14
RECV
18
Number of words to be received
×
2 + 14
CMND
Number of bytes in command
data + 10
Number of bytes in response
data
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)
Summary of Contents for C200HW-CLK21
Page 3: ...iv ...
Page 9: ...x ...
Page 12: ...xiii TABLE OF CONTENTS Index 367 Revision History 373 ...
Page 13: ...xiv ...
Page 19: ...xx ...
Page 57: ...32 Application Precautions Section 1 5 Example CX Programmer Response Timeout Setting ...
Page 69: ...44 Message Service Procedure Section 2 2 ...
Page 111: ...86 Constructing Networks with Repeater Units Section 3 4 ...
Page 154: ...129 Setting Data Links Section 5 2 Device Information Setting Data Link Tables ...
Page 261: ...236 Response Codes Section 6 7 ...
Page 297: ...272 Message Delay Times Section 8 4 ...
Page 353: ...328 Handling Precautions Section 9 6 ...
Page 364: ...339 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 365: ...340 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 369: ...344 Standard Models Appendix A ...
Page 391: ...366 Using the Relay Terminal Block Appendix C ...
Page 397: ...372 Index ...
Page 401: ...376 Revision History ...