Operation
Atlas
®
Digital Amplifier Complete Technical Reference
57
4
The SPI Status Register is not directly read via an Atlas command. It is read as part of SPI header processing. See
Section 5.2.1, “Header Return Words”
for more information. In addition, it may be selected as a traceable variable.
for more information on tracing.
4.8
Safety Processing Functions
Atlas provides a number of amplifier control features that automatically detect and manage safety-related conditions.
In addition, Atlas can signal when various conditions, safety or otherwise, occur.
The subsequent sections describe these features.
4.8.1
Overcurrent Fault
Atlas supports automatic detection of excessive current output. This fault occurs when the motor, the wiring leading
from Atlas, or Atlas unit’s power stage becomes short circuited.
An overcurrent fault will cause the following events to occur:
• The current loop and power stage modules are disabled, thereby halting further motor output.
• The Drive Fault Status register records an overcurrent fault condition.
• The Event Status register records a drive exception condition.
To recover from this condition the user should determine the nature of the fault using the
GetDriveFaultStatus
command. It may be desirable to power down Atlas to check connections or otherwise correct the Atlas-attached
hardware so that the problem does not occur again.
If the condition is resolved but Atlas is not power cycled, the following sequence should be used to restore the drive
to normal operation:
• Clear the fault condition using the
ClearDriveFaultStatus
command.
• Clear the drive exception bit of the Event Status word using the
ResetEventStatus
command. It is not
possible to re-enable the current loop or the power stage module if the drive exception bit is still active.
6
Disabled
Echoes the Disabled bit of the Drive Status register. Set 1 when the
Enable
pin
is inactive. Cleared 0 when the
Enable
pin is active.
7
Instruction error
Echoes the Instruction error bit of the Event Status register. Set 1 when an
instruction error occurs. This may be due to an incorrect command transmis-
sion, an Atlas-detected checksum error, or various other SPI interface com-
mand-related conditions.
8
Reserved
May contain 0 or 1
9
Over temperature event
Echoes the overtemperature bit of the Event Status register. Set 1 when an
overtemperature fault occurs.
10
Drive exception event
Echoes the drive exception bit of the Event Status register. Set 1 when a drive
exception event such as bus voltage fault, watchdog timer fault, over current
fault, occurs that causes Atlas to disable output.
11
Output clipped
Echoes the output clipped bit of the Drive Status register. Set 1 when current
loop output clipping is occurring. Cleared 0 when output clipping is not
occurring.
12
Foldback event
Echoes the foldback bit of the Event Status register. Set 1 when current fold-
back occurs.
13-15
Reserved
May contain 0 or 1.
Bit
Name
Description
