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Polled Read/Write/Init
On every transaction scan, a read target device register transaction occurs unless a local register value
has changed. The write transaction only updates those local registers that have changed in value. If several
non-consecutive local registers (contained in a single mapping entry) change value between transaction
scans, it takes several consecutive scans to write each changed register.
When the i3 is placed in RUN mode,
the initial action for this mapping type is a write target register
transaction.
This transaction initializes the target device register(s) to match that of the local (i3)
register(s). Thereafter, any change to the corresponding i3 register(s) triggers a write operation to the
remote device.
The initial write transaction does not occur until after the first logic scan of the i3. This allows registers to
be initialized locally before Writing to the target device register(s).
Triggered Read
A read transaction is triggered by a high level on a separately designated I3 (binary) trigger register. Once
the read transaction is complete (or the device is offline), the i3 trigger register is cleared by the i3. This
update type can be used for occasion data accesses such as retrieving trend data.
NOTE
: This operation increases the associated transaction scan time and can cause the
Update Interval
Exceeded Counter
to increment on a tightly adjusted update interval.
Triggered Write
A write transaction is triggered by a high level on a separately designated I3 (binary) trigger register. Once
the write transaction is complete (or the device is offline), the i3 trigger register is cleared by i3. This
function can be used for occasion data accesses such as sending recipe data.
NOTE
: This operation increases the associated transaction scan time and can cause the
Update Interval
Time Exceeded Counter
to increment on a tightly adjusted update interval.
