SPB
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When the SPB(-E) is starting up, the FPGA first tries to load the design (field bit stream) from
the flash memory. If not available, it loads a fully functional backup bit stream called factory
bit stream whose primary purpose is to get the system up to a point where a valid bit stream
can be loaded to the flash memory.
During startup the ELCB checks the SPB(-E) bit stream version.
14.4.1 Protection
All external interfaces are protected against short circuits (limiting the output current or with
current measurement and power switches).
14.4.2 Measurements Provided for Diagnostics
The on-board diagnostics supervises essential board functions like power supply and clock
synchronization. A watchdog mechanism checks for valid connection to the ELCB. In case of
a failure the board will reset and put electronics and valves into a safe state.
The software running on the ELCB may notify the user about abnormal events.
Status/Errors
The SPB(-E) can perform the following checks:
• Power supply voltages.
• Short circuits / disconnected lines at sensor interface connectors and connection to VPSB
(variable power supply board).
• Helium level measurement current source status (operational, correct current, broken
sensor).
• Valve block temperature.
• Emergency lift air status (used in CryoProbe systems).
Gas Flow and Pressure Measurements
The gas flow channels for VT and probe flush gas are equipped with flow sensors. These are
used for gas flow regulation and for diagnostic purposes. A pressure sensor checks VT gas
pressure.
Temperature Measurement
There is a PT1000 resistor built into the valve block providing temperature measurement.
Sample Down Detection Circuit
The sample down signal is continuously measured using a fast sampling A/D converter. This
feature provides superior adoption of the reflection sensor to different NMR spinners.
14.4.3 Calibration
There are no calibration settings to store on the SPB. The ELCB has full control over the SPB
hardware and provides methods for setting up the sample lift, helium level measurements
and nitrogen level measurement (SPB-E only). Spin calibration known from former systems is
no longer necessary.
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General