THORLABS SPCM A Series, Руководство по эксплуатации

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5 Maintenance and Service
© 2019 Thorlabs
47
During measurement, the software indicates lost USB connection
ð
Check if the SPCM is powered (power supply connected, SPCM switched on, green LED in
on), check the USB connection.
ð
Possibly, due to high data processing load, the SPCM micro controller was unable to pro-
cess USB operation. Switch the SPCM off and on again, reconnect and lower the measure-
ment speed. Array measurement (up to 1,000 bins per array) is safe under point of micro
controller load.
In Table display, during measurement only a fixed number of lines is displayed (e.g., 1
through 35)
ð
Use the scroll bar to scroll down in order to display further measurement data. The table is
not automatically scrolling to avoid lowering of measurement speed.
USB overload
This error message appears particularly when short bin lengths and small intervals between
bins are set.
ð
Change to Array measurement.
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Alternatively, extend time between bins (preferred) or bin length.
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In case of a triggered mode, lower the trigger frequency (if External Gating mode. lower the
gating pulse frequency).
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Measurement speed also depends on the viewed panel and CPU load. The fastest panel is
Alignment, followed by Table, Graph and Bar. The larger the total GUI size, the higher be-
comes CPU load.
ð
In certain cases, the USB performance can be improved by connecting of a High Speed USB
2.0 hub between SPCMxxA and the control PC.
No external triggering / gating possible
The signal level at Gate / Trigger In is TTL compatible, however (see Technical Data) this input
has an impedance of 50
W
, so that pulse amplitudes from a standard function generator may
be lowered.
ð
Make sure, your trigger / gating pulse source is capable to work on a 50
W
load.