Siemens SIMATIC S7 Equipment Manual page 10

Product Overview
Functionality
Use
1-2
Asynchronous mode
The selected sensors operate asynchronously (i.e., each sensor operates with
its own specific sensor measuring cycle time). The measuring cycle time is
the time available to the sensor for one measurement. This time can be set
separately for each sensor. Cycle time and measuring cycle time are not de-
pendent on each other. At the end of the measuring cycle time, the counting
values allocated to this sensor are transferred to the input area of the dual
port RAM.
The SM 338 module is equipped with the following functions.
Each sensor can be parameterized separately.
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Cycle time and measuring cycle time can be parameterized separately
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(and with different lengths).
Global enabling of an end-of-cycle alarm (i.e., process alarm) can be
S
parameterized.
Global enabling of diagnosis alarms can be parameterized.
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Sensor-related enabling of the diagnoses can be parameterized.
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Sensor-related enabling of wire break monitoring can be parameterized.
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Firmware monitoring via watchdog
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Indication of error states via two LEDs
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Module parameters can be reassigned during normal running operation.
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The main application area of the SM 338 is with plastics processing ma-
chines. Particularly with injection molding and blow molding machines, ul-
trasonic sensors are being used increasingly for position encoding. The
SM 338 is the direct link from the sensor to the S7-300 programmable con-
troller.
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SM 338 Equipment Manual
(4) J31069-D401-U1-A0-7618