Emerson Site Supervisor, User Manual

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5-16
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Site Supervisor Controller User Guide 2.0 026-1800 Rev 3 02-AUG-2016
If a daily schedule is not defined for a day of the week,
the control algorithm searches back in time for the last
defined state change. If no daily schedules are defined, the
output of the schedule is set to OFF. The DAY SCHED
input provides which day of the week or holiday schedule
to follow. When DAY SCHED input indicates that a
holiday is active, all schedules follow the selected holiday
schedule. If a holiday is entered and a schedule does not
have the selected special daily schedule defined, then it
reverts back and uses the regular schedule for that day of
the week.
If any of the maintenance schedules are activated, that
maintenance time schedule shall be used as the current
schedule. Time until next change of state and time since
previous change of state will be given in minutes. During
bypass, override, or demand control, TUCOS output is set
to maximum TUCOS value and TSCOS reflects the actual
time since change of state.
5.7.7 Control Override
When the EMERGENCY input is active, the normal
control algorithm is overridden and CONTROL OUT is
immediately forced to the value specified by the
EMERGENCY OUT parameter.
Slave Schedule
The ON/OFF times of the schedules (except for
maintenance schedules) can either be absolute or relative.
When the times are relative to the corresponding Master
events, positive time represents how much time after the
Master event and negative time represents how much time
ahead of the Master event. There is at most one relative
time for either ON time or OFF time for a single day.
The following illustrates the Master Schedule DAY
SCHED Output with the Slave schedule behavior:
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Maintenance Schedule
- follow the Master's
maintenance schedule. Normal day of week schedules are
ignored even if they are active.
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Holiday Schedule/Normal Day of Week
- if
Maintenance Schedule is active, run a Maintenance
Schedule. A relative event time of the corresponding
schedule is used to modify the master's schedule while the
absolute event times take precedence over the Master's
events.
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Bypass, Override, or Demand Shed active
(TUCOS=MAX_TUCOS)
- events with negative relative
times start immediately. If the delay (as indicated by
positive relative time of Slave's event) is longer than the
duration of the Master's special event, the Slave does not
react to that Master's special event.
5.7.8 Control Bypass
When the BYPASS TO ON input is active, the control
output is forced to the ON state regardless of normal
schedules. Likewise, when BYPASS TO OFF is active,
control is forced to the OFF state. BYPASS TO ON has
the higher priority over BYPASS TO OFF.
5.7.9 Control Override
When the EMERGENCY input is active, the normal
control algorithm is overridden and CONTROL OUT is
immediately forced to the value specified by the
EMERGENCY OUT parameter.
5.7.10 Special Conditions
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Cold Reset
- When the application has a Cold
Reset request, the OUTPUT will be set to
NO_VALUE.
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Warm Reset
- When the application restarts from a
power outage or something else, a Warm Reset is
requested. The control loop scans back to find out
the last event before the current time.
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Uninitialized Inputs
- If a NO_VALUE appears on
DAY SCHED input, the control's OUTPUT falls
back to the normal day of the week.
If a NO_VALUE appears on any other input, the
input value is forced to a predetermined (hard
coded) default value and the control algorithm
continues to operate normally.
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Failed Inputs -
If a failure is detected on the DAY
SCHED input, the control's OUTPUT falls back to
the normal day of the week.
If a failure is detected on any other input, the input
value is forced to a predetermined (hard coded)
default value and the control algorithm continues to
operate normally.
5.7.11 Priority of Services
The application prioritizes its activities such as:
1.
ENABLE input
- The Enable input determines
whether the schedule will be enabled (ON) or
disabled (OFF). When disabled, all the schedule's
outputs, are set to NONE. If this input is not
defined, the controller assumes it to be ON.
2.
EMERG OVERRIDE
- The Emergency
Override input allows the user to override the
schedule Output to a fixed digital value. When
ON, the schedule overrides the Output to the
value specified in the Emergency Out field.
3.
BYPASS
- When the Bypass to ON input is ON,
the schedule ignores its own scheduled events