Performance Motion Devices Prodigy Series User Manual page 39

2.3.4 Card Watchdog Timer
To enhance the overall safety of the card, a watchdog function has been included. When enabled, the watchdog will
automatically trigger a card reset if communication to it should be lost. See Section 2.6.2, "Reset," on page 50 for a
description of the actions and signal changes that occur after a card reset.
To enable the card watchdog timer, the
enabled, the watchdog timer will time out, causing a hard reset, if another write to address 4 with a value of 0x5562 is
not received within 104 mSec. As long as a watchdog value is written to address 4 within the 104-mSec interval, no
reset will occur and motion operations will proceed normally. Once enabled, the watchdog mechanism cannot be
stopped until a reset or power cycle occurs.
After powerup or card reset, if no command is sent to the watchdog address, then the watchdog will remain disabled.
The watchdog is disabled by default at power-up. When the watchdog timer times out and triggers a reset, it also
disables itself.
In addition to the low-level
ReadIO
and VB-Motion: SetWatchDog
value 0x5562.
2.3.5 Undervoltage Monitor
To enhance reliability under a variety of electrical conditions, an undervoltage detection circuit has been included. This
circuit triggers a hard reset when the voltage has dropped to an unsafe level. Resetting the Prodigy/CME PC/104 card
will have the result of setting all motor command outputs to zero, thus allowing the motors to come to a safe stop. An
undervoltage condition is detected when the 3.3V internal supply on the card drops below 2.7V. See Section 2.3.6,
"Reset Monitor," on page 39 to determine if a reset was caused by an undervoltage condition.
2.3.6 Reset Monitor
During normal operations, the Prodigy/CME PC/104 card is only reset during power-up. There are, however, several
other ways that the Prodigy/CME PC/104 card can be reset. See Section 2.6.2, "Reset," on page 50 for a complete
description of how the card can be reset. A reset serves the purpose of initializing values and bringing the Prodigy/
CME PC/104 card to a known and consistent state.
To determine the cause of a card reset, special instructions to read the reset source have been provided. The command
ReadIO with an address of 2 should be used. The following table details the encoding of this I/O address word.
I/O Bit
Address Location
2 0-10
11
12
13
14
15
Once a reset condition has occurred, the reset status stored at address 2 (described in the preceding table) can be
cleared by a WriteIO command to address 2 with a value of zero (0).
Prodigy/CME PC/104 User's Guide
command is used to send a value of 0x5562 to address 4. Once
WriteIO
and commands, the following command is also supported by C-Motion
WriteIO
. This command provides a clearer and simpler interface by automatically sending the
Signals
Reserved
C-Motion Engine user application code fault. A 1 value in this bit indicates an instruc-
tion or address access fault.
Commanded reset. A 1 value in this bit indicates a card-level reset commanded via the
PRP action Reset.
Undervoltage detection: a 1 value in this bit indicates a reset caused by undervoltage
detection.
External signal: a 1 value in this bit indicates a reset caused by the external Reset sig-
nal, pin 91 of the GP Connector (J6)
Card Watchdog timeout: a 1 value in this bit indicates a reset caused by the card
watchdog timeout. See Section 2.3.4, "Card Watchdog Timer," on page 39
description.
Operation
for a
2
39