Emerson E2 Manuel D’Utilisation

If desired, delays may be specified for stage activation 

and deactivation. Also, the definitions of OFF and ON 
may be redefined as either ON, OFF, or NONE.

The PWM cell converts the control output percentage 

into a periodic ON pulse. A “pulse” in this cell is a con-
stant period of time that consists of one ON event and one 
OFF event. The PWM cell takes the PID percentage and 
turns the output ON for an equivalent percentage of the 
total pulse period. In other words, if the PID output is 60% 
and the pulse period is 30 seconds, every 30 seconds the 
PWM output will be ON for 60% of 30 seconds (18 sec-
onds) and OFF for the remaining portion of the 30-second 
period. Once the period has ended, the PWM Cell reads 
the PID output again and the process is repeated.

Time Schedules are used for timed activation and 

deactivation of loads and for providing occupied and 
unoccupied building times for occupancy-driven systems 
(such as Sensor Control, Lighting, and HVAC).

There are four different types of schedules used by the 

E2. Brief description of each of these are given below:

Master schedules are the main scheduling unit used 

by the E2. A master schedule consists of up to 15 sched-
uled ON/OFF event pairs, which may be programmed to 
occur on any individual date and time or series of dates 
and times. Master schedules may also drive slave sched-
ules.

Slave schedules are similar to master schedules, 

except their operation is driven by a master schedule. 
Slave schedules, generally, are alterations of the master 
schedule’s event times. The ON/OFF times in a slave 
schedule may take place either at specific defined times of 
the day or relative to the times given in the master sched-
ule. For example, a master schedule may say: “The build-
ing is occupied from 8:00 a.m. to 9:00 p.m.” while one of 
its slave schedules says “Dim the building lights 15 min-
utes before the store closes.”

Slave schedules may also be mastered by other slave 

schedules to create a series of stacked schedules.

Holiday schedules are used to tell master and slave 

schedules that a special day or event is occurring. For 
example, master schedules and their corresponding slave 
schedules may be programmed with special holiday 
events, such as “Keep all lights off during Holiday x.” The 
holiday schedule’s job is to inform the schedules to which 
it is connected, “Today is Holiday x.” 

Although holiday schedules are used exclusively by 

Time Scheduling applications, they are set up as individual 
applications separate from Time Scheduling. See Section 
11.14.2, Holiday Schedules for more information.

Temporary schedules are technically not schedules 

but temporary override functions that may be made to 
exist within an individual master or slave schedule. Tem-
porary schedules are used to temporarily override the ON/
OFF instructions of an individual master or slave sched-
ule. Generally, temporary schedules are only used for one-
shot applications, such as keeping the lights on an extra 
hour for a single night. Temporary schedules override all 
other events within a master or slave schedule, including 
holidays.

Master schedules and slave schedules consist of up to 

15 pairs of events. Events are simple commands to turn 
the schedule output either ON or OFF at a particular time 
within a range of days. Events are usually programmed in 
pairs, so that during a specified range of days the schedule 
output can be turned ON and OFF at a particular time 
within the same day. However, events may be pro-
grammed singularly (on OFF or one ON command per 
day). Events may be programmed to take place on any or 
all days from Sunday to Saturday. In addition, events may 
take place on any or all of four holiday (or “special”) 
dates, called HD1, HD2, HD3, and HD4. Holiday sched-
ules are used to tell the master or slave schedules when 
these special dates occur.

Master schedule events always occur at specific times 

of the day. In other words, when you program an event 
pair in a master schedule, you must specify two specific 
times of the day the events will occur. These types of 
events are called absolute events.

However, when programming event times in slave 

schedules, you may choose to enter event times that are 
relative to its master schedule’s ON and OFF times. These 
types of events are called relative events. They are pro-
grammed not as absolute times but as amounts of time 
before or after its master schedule’s events.

For example, suppose a master schedule is set up to be 

ON at 8 a.m. and OFF at 9 p.m. every day of the week, and 
you wish to set up a slave schedule so that its output 
comes ON 15 minutes before the master comes ON and 
OFF 15 minutes after the master goes OFF. To do this, you 
would set up the slave schedule to come ON at -00:15 and 
OFF at +00:15 every day of the week. The slave schedule 
will automatically determine the correct ON and OFF 
times.