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150
Bus Parameters
Appendix A
The parameters to calculate are:
• Target Rotation Time
• Min Slave Interval
• Watchdog timeout
• Data Control Time
These four values depend on the number of slave stations allocated to the PROFIBUS-DP Master Unit, the
number of I/O bytes each of the slave stations will exchange with the Master Unit, and how many other Master
Units are on the PROFIBUS network at the same time.
Furthermore, the Unit will require additional time to process the PROFIBUS I/O data and exchange this with
the PLC CPU. Based on this, the following empirical formula is used:
Min. Slave Interval = A
1
+ (B
1
* slave stations) + (C
1
* bytes to transfer) +
(bits per
µ
s)*((A
2
* slave stations) + B
2
* modules) + (C
2
* Words to exchange)
[1]
Target Rotation Time T
TR
=
å
(Min. Slave Interval)
[2]
T
WD
= T
TR
+ 20000
[3]
Data Control Time = (T
WD
* 7) * 100 / Baud rate
[4]
Based on measurements, the following values have been determined for the 6 factors in equation [1]:
Содержание SYSMAC CJ1W-PRM21
Страница 2: ...iv...
Страница 36: ...22 Basic Operating Procedure Section 1 5...
Страница 52: ...38 Defining PROFIBUS DP in the Software Section 2 5...
Страница 112: ...98 Allocated CIO Area Words Section 4 2...
Страница 122: ...108 Command Response Reference Section 5 2...
Страница 160: ...146 Replacing the Unit Section 7 8...
Страница 174: ...160 Appendix...
Страница 180: ...166 I O Data Conversions Appendix D...
Страница 186: ...172 Configurator Error and Warning Messages Appendix E...
Страница 187: ...173 Index...
Страница 188: ...174 Index...
Страница 190: ...176 Revision History...