PC104 View Datasheet(PDF) - PMD
Part Name
Description
MFG CO.
'PC104' PDF : 70 Pages View PDF
2
Operation
2.3.5 Watch Dog Timer
To enhance the overall safety of the card a watch dog function has been included, allowing the
motion processor to be automatically reset if communications to/from the host, for whatever reason,
should be lost. Resetting the motion processor will have the result of setting all motor command
outputs to zero, thereby letting the motors come to a safe stop.
ReadIO and WriteIO commands
To enable the watchdog timer, a WriteIO command is sent to address +4, with a specific value of
0x5562. Once enabled, the watchdog timer will time out, causing a motion processor reset, if another
write to address +4 with a value of 0x5562 is not received within 104 milliseconds. As long as a watch-
dog value is written to the +4 address within a 104 millisecond interval, no reset will occur, and motion
operations will proceed normally.
If no command is sent to the +4 location, then watchdog will remain disabled. Thus watchdog
disabled is the default condition upon power-up.
C-Motion commands
In addition to accessing these signals using the C-Motion command PMDWriteIO, you can use
card-specific C-Motion functions for this purpose. The available card specific functions for this
feature are:
C-Motion
command
PMDMBSetWatchDog
Arguments Function description
axis handle
This function writes to the correct
value to the watchdog register, so
that for the next 104 milliseconds
the card will not be reset by the
watchdog circuitry.
Connections & associated signals
The Watchdog timer is an internal function of the card. Thus there are no signals directly associated
with this function.
2.3.6 Under Voltage Monitor
To enhance reliability under a variety of electrical conditions, a special under voltage detection circuit
triggers a motion processor reset when the voltage has dropped to an unsafe level. Resetting the
motion processor will have the result of setting all motor command outputs to zero, thereby letting
the motors come to a safe stop.
An under voltage condition is detected when the 5V supply to the card, provided through the PC/104
bus, drops below a specific voltage specified by an under voltage supervisory device. The typical under
voltage threshold is 4.625V, while the min. and the max. values are 4.50V, and 4.75V, respectively.
Connections & associated signals
The under voltage detector is an internal function of the card. Thus there are no signals directly
associated with this function.
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Navigator-PC/104 User’s Guide
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