Danfoss MCO 305 Design Manual page 138

MCO 305 Design Guide
__ APOSS Tools __
Usage Notes for Polling Mode
If the Free Run Oscilloscope is being used in Polling
Mode, then add the curves as usual but instead of
selecting a group for the curve, the Polled (no
group) option should be selected.
Recording is then started in the normal way using the Start toolbar button. The Oscilloscope will retrieve
curve data by "polling" each curve on a regular time interval. Each curve is polled by sending an explicit
SDO request for its value. The user can set the polling time interval (i.e. the polling rate) using the Settings
→ Oscilloscope menu command. The Oscilloscope Window will look similar to the following:
When the Oscilloscope is actively recording data, the window title (top left in the above example) will
contain a string similar to "[50ms 25%]". The "50ms" is the polling rate. In this example, each curve will be
polled once every 50 milliseconds. The "25%" gives an estimate of how much of the communications
network is being consumed. This percentage will go up as more and more curves are being polled. A
percentage higher than 100% indicates that the Oscilloscope can no longer poll all curves in each time
interval. If this happens, the user should either reduce the number of curves being polled or increase the
poll time interval.
The number of curves that can be polled and the rate at which they can be polled, cause a significant
limitation to the Oscilloscope when running in polling mode. Many fewer curves can be polled, and much
less often, than is the case if PDO messages are used. The result is that the recorded data is much less
detailed.
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