CHANNELS (BOZZA)
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[JSup] I/O system is organizes in channels that
group [tag I/O hooks] and defines the way they are
read/written. Every channel is bound to a [driver]
and to a driver specific a device. Some features: *
Channels can perform timed or triggered read or
event unsolicited read (according to the
protocol/driver capabilities). * Channel read can
be [requested by a window]. * Writes can be
triggered and/or done on tag change. Channels are
comparable with FactoryLink I/O tables. The
[Channel list] can be accessed with the menu Tools
/ Edit channels (or Ctrl+H keys). 1. Channel
configuration * The [I/O driver] that the channel
has to use for its communication, it cannot be
changed once the channel is created. * Name: an
[unique name] that will identify the channel. *
Drive dependent info: a button that open a driver
specific dialog that provide configuration about
the device and driver specific configuration of the
channel. * Item prefix: a fixed text that will be
prepended to every item of the channel [I/O hooks],
this can be useful for some drivers ([SNMP] or
[MQTT]) to not to have to include a fixed prefix to
every [I/O hook]. * Channel active condition: can
be a constant or calculated expression that enable
/ disable the channel at all if, for example, a
channel have to be active only on a certain JSup
server or if you want to disable a channel at all
but you don't want to delete it. * Block read: a
block read requesta all [I/O hooks] value (except
for write only [I/O hooks]) from the remote device,
when the Block read trigger [expression] changes to
a non false (or 0) value.
The Block read trigger is normally a single [tag]
forced to true (or 1) to perform the read.
The End read tag, if specified, is a [tag] that
will be forced to true if all the [I/O hooks] have
been read successfully, or forced to false if the
block read is not successful (even if [I/O hooks]
are partially read: some read and some not). This
tag will receive also the status of a Continuous
read completion. * Continuous read: a timed basis
read that can be enabled with a constant or
variable expression (Read enable condition) and
repeated at a given millisecond rate (Update time:
constant or an [expression]). Some [driver] enable
the possibility to read only active items, the [I/O
hooks] of listened tags (the ones those are
displayed in active [window]). Active [windows] can
specify the read of one (or more) channels and the
requested rate: the shorted rate will be used. *
Block write: all the [I/O hooks] of the channel
(except the read only ones) can be written at once
when the Block write trigger [expression] (normally
a single boolean tag) changes to a true (or non
zero) value.
The End write tag, if specified, will be forced to
true if all the [I/O hook] values have been written
successfully, or to a false value in case of some
write failure. * Write on change can be enabled to
perform single write for every [I/O hook] whose tag
change value (or whose value is forced). The Write
on change disable can be configured with an
[expression] (normally a single [tag]) that when
non false disable the write on tag changes. This
can be useful if a massive tag change is expected
and you what to write all tag at once with a Block
write. * Poor quality to tag filter: is the time
after a bad [I/O hook] value read after which the
tag will be set in a poor [quality] status. * Alarm
only: a flag for [Unity] import feature only. *
Auto I/O hook JavaCode fun.: see [JavaCode function
provided IOHooks].