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Each entry can be configured for one of two types of initiating a transaction:
Polled and Triggered.
Polled
type entries initiate a transaction with the remote device on every transaction scan. Triggered type entries
only initiate a transaction when a corresponding local (i3) binary trigger register is
set
. Once a triggered
type of transaction completes, the protocol device driver
resets
the local (i3) binary register to indicate
completion.
These basic types are also subdivided into Read or Write operations. For polled operations, a Read
operation only reads from a remote device. Likewise, a Read/Write operation continuously reads from
the remote device unless the target I3 register value changes from one ladder scan to another. In this
case, the new i3 value is written to the target device. For triggered operations, only a Read or Write action
is available.
When downloaded to the i3, the Scan List is scanned sequentially to generate data transactions with the
remote device. This transaction scanning can be on a continual basis (
automatic
) or controlled from ladder
logic (
manual
) once a complex connection is programmatically created (i.e., dialup modem). The specific
transaction-scanning mode is selected from the
Network Config
menu.
Please refer to the I3 configurator Help file for more information on Downloadable Protocols
Configuration. After opening the I3 configurator Help file, select
Contents
Networking and
Communications
Protocol Configuration.
