63
Data Link Characteristics
Section 4-11
Manual Generation
When data link tables have been generated manually, the communications
cycle time can be set to a constant value or generated automatically.
The communications cycle time can be set as a constant from 5 to 255 ms in
increments of 1 ms using the Support Software to eliminate variations caused
by noise or other factors. When the communications cycle time is not set as a
constant, it will be generated automatically according to the equations below.
Round the result of the calculation to the nearest millisecond.
Communications cycle time (coaxial cable systems) =
Maximum node address
×
0.085 ms + maximum number of frames
×
0.654 ms + number of polled units
×
0.75 ms + number of Link Units
×
0.056 ms + total number of words
×
0.01 ms + 1.322 ms
Communications cycle time (optical fiber cable systems) =
maximum node address
×
0.1115 ms + maximum number of frames
×
0.77
ms
+ number of polled units
×
0.75 ms + number of Link Units
×
0.056 ms
+ total number of words
×
0.010 ms + 1.322 ms
Note
The present and maximum values of the communications cycle time can be
monitored from the Support Software.
Example Calculations
The examples below calculate the communications cycle time for both coaxial
and optical fiber cable with the following characteristics:
Maximum node address: . . . . . . 62
Maximum number of frames: . . . 10
Number of polled units: . . . . . . . 4
Number of Link Units . . . . . . . . . 32
Total number of words . . . . . . . . 2,000
Communications cycle time (coaxial cable systems) =
62
×
0.085 ms + 10
×
0.654 ms + 4
×
0.75 ms + 32
×
0.056 ms + 2000
×
0.01 ms + 1.322 ms
= 37.924 ms (38 ms after rounding)
Communications cycle time (optical fiber cable systems) =
62
×
0.1115 ms + 10
×
0.77 ms + 4
×
0.75 ms + 32
×
0.056 ms + 2000
×
0.01 ms + 1.322 ms
= 40.727 ms (41 ms after rounding)
Note
Data links might not operate correctly if the communications cycle time is set
to a value shorter than that generated automatically by the system. If the LNK
indicator on the front of a CS-series SYSMAC LINK Unit (CS1W-SLK11/12)
flashes quickly (at approximately 100-ms intervals), either automatically set
the communications cycle time for the data link table, or manually set the
communications cycle time to a longer value.
Changing the Communications Cycle Time
When the communications cycle time is generated automatically, it can be
changed by changing the other network parameters on the Support Software.
The default values and setting ranges of the other network parameters are
shown in the table below.
Use the following formulas to calculate the change in the communications
cycle time that results from a change in other network parameters. A positive
Network parameter
Default value
Setting range
Maximum node address
62
2 to 62
Number of polled units
4
1 to 62
Maximum number of frames
10
5 to 255
Summary of Contents for CS1W-SLK11-21 - 06-2004
Page 1: ...Cat No W367 E1 02 SYSMAC CS1W SLK11 21 SYSMAC LINK Units...
Page 2: ...CS1W SLK11 21 SYSMAC LINK Units Operation Manual Revised June 2004...
Page 3: ...iv...
Page 5: ...vi...
Page 9: ......
Page 11: ......
Page 17: ......
Page 49: ......
Page 107: ......
Page 139: ...122 FINS Commands for SYSMAC LINK Units Section 6 4...
Page 143: ......
Page 170: ...153 Appendix B Dimensions CS1W SLK11 Optical SYSMAC LINK Unit Unit mm...
Page 171: ...154 Dimensions Appendix B CS1W SLK21 Coaxial SYSMAC LINK Unit Unit mm...
Page 177: ......
Page 179: ......
Page 195: ......
Page 199: ......
Page 202: ...SYSMAC CS1W SLK11 21 SYSMAC LINK Units Cat No W367 E1 02 OPERATION MANUAL...