User Manual

Logical I/O blocks
Data storage
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CM110664en_07 235 | 353
19 Logical I/O blocks
I/O blocks are used to register and transmit raw data to and from the plant, and
to convert, process and integrate it into the program.
The following options are supported:
● Raw data from or to the input or output modules.
● Raw data from or to the PPS2 interface (room units) (not for the modular
series PXC…D)
● Data referenced via the Technical Designation (TD) and accessed either in
the same automation station (without a connection), or peer-to-peer via
BACnet services.
● Data made available via a Discipline I/O of a room automation station or
third-party device.
The term I/O blocks refers collectively to the individual input blocks and output
blocks.
● Input blocks are used to enable an input signal (e.g., a measured value) in
the program to be handled as a process value.
● Output blocks are used to enable a process value to be transmitted as an
output signal (e.g., a positioning command).
Value blocks act as a link between program pins, and are used to temporarily
store a process value, and if necessary, to display it on a client operator station.
A special version of the value block, the Value block for operation provides a
simplified means of operation from an operator client (without the facility to
override values manually).
Counter Input blocks (CI blocks) are used to enable a counter value (e.g., from
a gas or electricity meter) to be processed in the application as a real-number
process value. In this process, the counter value (pulse) is converted in the
block into the associated physical variable.
Integration I/Os (Discipline I/O blocks) are used, e.g., to integrate room
automation or third-party devices
Input blocks Output blocks Value blocks Value blocks for operation
Analog Input (AI, AI RED) Analog Output (AO, AO RED) Analog Input (AVAL) Analog Input (AVAL_OP)
Binary Input (BI, BI RED) Binary Output (BO, BO RED) Binary (BVAL) Binary (BVAL_OP)
Multistate Input (MI, MI RED) Multistate Output (MO, MO RED) Multistate (MVAL) Multistate (MVAL_OP)
Counter Input (CI)
Accumulator (CI ACC)
Discipline I/O
I/O blocks are displayed in two different views:
● The program view shows an I/O block with the pins and attributes required
for configuration purposes and to create the program. This is the display
format used in Xworks Plus (XWP).
● The system view shows the I/O blocks as standard BACnet objects. These
BACnet objects and the associated properties are then available to clients
from where they can be operated and monitored.
All the blocks listed above are implemented in accordance with the BACnet
standard. Therefore additional functions are available, such as alarm
management. These blocks incorporate a mechanism which acts as an alarm
source for blocks available as standard BACnet objects in the BACnet network.
By use of various BACnet services, a given event is displayed as an alarm event
on the relevant clients from where the alarm can be processed, that is, viewed,
acknowledged and/or reset.
In XWP these functions can be tracked via the relevant values at the block pins
in online test mode.
Program view and
system view
BACnet functions