Siemens SIMATIC S7-300 FM 350-1, Руководство пользователя

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Operating Modes, parameters and commands
7.4 Measuring modes
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
139
Isochronous mode
When operating in isochronous mode, FM 350-1 accepts the control signals output by the
control interface at time T
o
in each PROFIBUS DP cycle. As a result, all control operations
are executed in isochronous mode and take effect at the time T
o
. The reaction to the control
signals is reported within the same PROFIBUS DP cycle.
FM 350-1 returns a measured value and the status bits at time T
i
in each PROFIBUS DP
cycle
.
Each measurement starts and ends at the time T
i
.
Note
As you need to define the update time as an integer multiple of 10 ms for operation in non-
isochronous mode, and in integer multiples of the PROFIBUS DP cycle time for operation in
isochronous mode, you should also adapt the update time parameter when you toggle these
modes in order to retain the actual update time.
Commands in the measuring modes
You can control measurements at FM 350-1 by executing the following commands.
Table 7- 31 Commands of FM 350-1
Designation Description
Open and close gate You start the measurement by opening a gate, and stop it by closing
this gate.