BackPower Fault state
27 Jul 2012
The “Power Fault” state is not a commonly encountered condition. Usually it is only encountered when the battery has been removed without first suspending (briefly pressing the Power button, as recommended), attaching the wall charger, or performing a full Power Off. Though it may also be encountered in the following conditions.
- When operating with a "worn" battery that may need to be replaced (such as has exceeded its expected 500 full charge cycle life)
- Combined simultaneous high current voltage draw from system, expansion module, and/or external devices
Performing a manual Reset (pressing and holding the Power button for 5 seconds) clears this state. You may also want to purchase a replacement battery and/or reduce potential sources of current draw as discussed at the following web pages.
For background information, while in suspend and the battery is removed, the system (mainly RAM memory) is maintained for several minutes by a hardware super capacitor. This was implemented to give users the ability to “warm swap” batteries while in the field.
If the “Power Fault” state is ever encountered, all power has been and remains removed from peripheral ports (serial, USB, docking I/O pins, etc.) and embedded peripheral devices (Bluetooth, Wifi, etc.) until after a manual Reset (pressing and holding the Power button for 5 seconds). Power to peripherals is removed to preserve power for the processor and RAM to properly suspend automatically so the user then has an opportunity to resume after a power source is re-applied and be able to backup active data and properly shut down running apps before then performing a manual Reset. Previous product models which did not have this “Power Fault” state would just automatically perform a Reset (warm boot), wiping out RAM memory and running programs without regard to any potential for data loss or maybe memory corruption (such as if any app was actively writing to flash memory when the battery was pulled and then the Reset automatically occurred).
A patch utility is available for the Allegro MX Field PC which disables this Power Fault function if desired and enables a Critical Suspend function similar to our other products and previous Allegro models. When the patch is installed, it should allow the Allegro to automatically suspend during significant battery voltage dips, and re-enable all peripheral ports automatically after resume (without displaying the Power Fault message and requiring a manual Reset). See the following website for more information.
Allegro MX Downloads > Power-Fault-patch-utility
