Download Binary Output (BO) Object Technical Bulletin

Output Relay
Orientation
When the software issues a BO command (e.g., Start, Stop, On, or Off), it
must convert the binary code to a value that can be understood by the
hardware. For example, the hardware needs to know if a Start command
opens or closes the relay contacts.
Attributes to Set for Output Relay Orientation
The Output Relay attribute affects Output Relay Orientation:
Output Relay gives you flexibility in determining whether the Start
command opens or closes the relay contacts.
•
Specify Y (yes) if the output relay is closed in the State 1 (e.g., Start)
condition.
•
Specify N (no) if the output relay is open in the State 1 (e.g., Start)
condition.
Additional hardware information is covered later in this document, under
the section called Hardware Interface.
Command
Execution
Attributes
Affected by
Command
Execution
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Once the software has checked for priorities, Start/Stop constraints, and
heavy equipment delay, the BO Start or Stop command is executed. The
command causes the hardware and software to change accordingly.
•
Hardware--The relay contacts of the binary output device either open
or close, depending on the output relay orientation.
•
Software--A number of BO attributes update, including Commanded
Value, Commanded Feature, and Command Priority. If a feedback
object is assigned to the BO, the BO Status can change, as well. These
attributes are explained in more detail below.
The following attributes are affected by command execution:
•
Commanded Value is updated to reflect the command that was
executed, such as Start or Stop. This is displayed at the BO Focus
window. If the BO is locally controlled, Commanded Value will
display commands issued locally (by the ASC) to the output.
•
Current Value is the same as the Commanded Value if the BO
doesn’t have an associated feedback object. If feedback is assigned,
the BO Focus window displays the current value of the BI or BD
object. For example, the current value could equal On if a BI air flow
switch detects air from a supply fan.
•
Commanded Feature is updated to reflect the source of the
commanded value. Operator, Scheduling, Control Process, Multiple
Command object, Demand, Load Roll, Initial, Local Control, None, or
Override is displayed in this field at the BO Focus window.
Objects—Binary Output (BO) Object