Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 23
www.ScannerMAX.com
4.0 Fault monitoring and other protection circuitry
4.1
Fault Detection
The Mach-DSP includes protection circuitry that will disable the servo loop and
optionally set one or both of the user-defined TTL outputs to a prescribed logic level if
any of several monitored error conditions are detected.
The Mach-DSP protection circuitry monitors scanner position, scanner current, scanner
coil temperature (and body temperature if you use a thermistor as described in Section
3.5), servo board temperature, and scanner Position Sensor AGC health (including
scanner connector unplugged). The Mach-DSP protection circuitry may also optionally
monitor one or more user-defined TTL inputs.
When one of the monitored parameters goes outside of the prescribed maximum range
(whose range is user-adjustable for most parameters), the servo will shut down. Once
all faults are cleared, the servo will automatically reset in a controlled power-up
sequence that resets the integrator, enables the servo loop, and then gradually enables
the command input, and optionally indicating that the servo is ready using one or both
user-defined TTL outputs.
4.2
Fuses
Both of the X and Y Scanner drive outputs of the Mach-DSP are fuse-protected, to
prevent damage to either the scanner or the servo system in the event of a severe
electrical fault. Pangolin installs fuses whose rating is selected based on the RMS
power handling capability of the scanner being driven. The fuse is a Nano2 type,
series 0453 made by Littelfuse.
4.3
LED Indicator Lights
The Mach-DSP includes five separate LED indicator lights that may be used to
determine the operational status of the servo driver. These lights are located on the
front of the board and shown at the beginning of Section 3 above.
LED1 will illuminate yellow whenever there is communication between the Mach-DSP
and the PC (or external serial data interface).
LED2 will illuminate red several times per second, and gives an indirect indication of
how much time is spent in the servo algorithm and how often the power supply voltages
are being checked. This may be used for troubleshooting if called upon to do so by
Pangolin.
