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OPERATION
FIELD I/O WATCHDOG AND FAULTS
The 7I76 has a watchdog timer that will set all set a fault flag if host communication
does not occur at a minimum rate. Default watchdog time is 50 mS which means if not
accessed at a greater than 20 Hz rate, the watchdog will bite and disable the outputs.
When a fault flag is set, outputs can not longer be set and the host must first clear
the fault before normal operation can continue. This is also the 7I76s startup condition,
meaning the host must first clear the fault before starting normal operation. This is
normally handled by SSLBP.
FIELD I/O PARAMETERS
The 7I76 has several user settable parameters, but normally only a very few need
be changed in normal operation.
PARAMETER
TYPE
FUNCTION
NVBAUDRATE
UINT
Sets operate mode baudrate
NVUNITNUMBER
ULONG
Non-volatile unit number
UNITNUMBER
ULONG
Working unit number
NVWATCHDOGTIME
UINT
Non-volatile watchdog time in mS
WATCHDOGTIME
UINT
Working watchdog time in ms
OUTPUT
UINT
16 bits of output data
INPUT
ULONG
32 bits of input data
FAULT
UINT
7I76 fault register
STATUS
UINT
7I76 status register
7I76 15