7I76 15
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
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