Instruction Manual

Logic Functions - Book 1
DATABASE DESCRIPTION
2-10
2.4.2 Startup
The instrument supports startup logic with configurable power-down/restart duration periods
for warm and cold starts. The startup definitions are:
WARM Instrument was down for less than a configurable amount of time. Timers,
stack, PC, and so forth are reinitialized. The WARM START DURATION
defines the power-down/restart interval in the Interface block as a
millisecond time value of NONE (zero) to INFINITY (Times less than 1
second are not useful because of potential drift between the battery backed
and run time clocks). Warm start values are also used when the user
wishes to switch from the default database to the main database without
forcing cold start initialization of the main database. The option to download
the memory module on a warm start is also allowed.
COLD Instrument was down for a period of time longer than the warm start duration
but less than a configurable cold start duration. Function blocks are fully
initialized. The default value is INFINITY. If a memory module is present, it
will download to the instrument. The memory module could be write
protected with cold start values if the user wishes.
FROZEN Instrument was down longer than the configurable cold start duration. After
power-up, the instrument will go to the HOLD state and the operator must
issue a request for the instrument to go to RUN. Initialization is same as
cold start.
A shutdown (for example, spurious interrupt, watchdog, bad main checksum) information data
area is set aside at the beginning of the main battery backed RAM area, before the database.
Information in this area is used during power up to determine if the instrument previously
powered down normally, or shut down due to a fault termination condition. The information is
copied to the memory module as well.
If, during power up, the shutdown information indicates that the instrument previously
terminated with a fault condition, a diagnostic is set and the instrument runs the default
database (DEFAULT state). A second fault termination will not overwrite the shutdown
information and an operator message is required to clear the fault condition information, in
order that it is not cleared erroneously by a non-maskable interrupt (NMI)/power-up.
2.4.3 I/O Lock
The I/O lock feature allows output function block values not to be copied to the output module
block output value, and input module block values not be copied to the input function blocks
(field input values continue to be updated in the input module blocks). Output module block
values can be written to via messages. Data writes to output module blocks are accepted
when the block is in manual, or the instrument state is not run, or I/O lock is set. Data writes
to input module blocks are accepted only when the block is in manual.