Emerson E2 User Manual

The Digital Sensor Control module performs three 

basic functions:

• LOGICAL COMBINATION: Up to four inputs 

may be combined using standard logical combina-
tion methods (such as AND, OR, XOR, etc.) The 
result is the command output value, which can be 
used to operate a relay.

• BYPASS: The command output may be configured 

to be bypassed to a fixed value by a switch or but-
ton press.

• ALARMING: Alarms and notices can be generated 

based on the command value of all the digital inputs 
of the cell, plus occupancy, and schedules.

A Digital Sensor Control module has four inputs num-

bered 1 through 4. The logical combination of the Digital 
Sensor Control modules follows one of the following strat-
egies:

• FIRST - The first of the four digital inputs received 

will be used as the logical input value. This combi-
nation first looks at input #1. If the value of this 
input is undefined, it looks for other valid inputs, 
starting with #2 and descending in numerical order 
to #4.

• SELECT - The sensor module reads an analog 

input, which provides a numerical value from 1 to 
4. This number determines

• AND - The logical input value will be ON only 

when all sensor control inputs are ON. If one or 
more of them are OFF, then the logical input value 
will also be OFF.

• OR - The logical input value will be ON if one or 

more sensor control inputs are ON. If all of them 
are OFF, the logical input value will also be OFF.

• XOR - This combination strategy is exactly the 

same as OR, except when all sensor control inputs 
are ON, the logical input value will be OFF instead 
of ON.

• VOTE - If more than half of the sensor control 

inputs are ON, the logical input value will be ON. 
Otherwise, if 50% or less of the sensor control 
inputs are OFF, the logical input value will be OFF.

The Loop Sequence Control application’s main func-

tion is to read the value of an analog input, compare the 
value to a setpoint, and generate a single analog output 
value. This output value is represented in three different 
forms: a single analog value from 0% to 100%, up to eight 
digital stage outputs, and a digital pulse width modulation 
output. 

The output value(s) are generated by a PID Control 

cell, which takes into account both the input’s instanta-
neous value and its rate and direction of change. The PID 
Control algorithm is similar to the PID algorithm used by 
Pressure Control, except the Loop Sequence Control 
application is designed to be used in a wider array of 
applications.

There are two different types of cells in the Loop/

Sequence Control Application: control cells and output 
cells. The control cells have a part in determining the PID 
output percentage. The output cells convert this PID per-
centage to staged digital and pulse width modulation acti-
vations.

The five control cells in the Loop/Sequence Control 

application act as “steps” in determining the final PID per-
centage.

Step 1: Select - The Select cell determines whether the 

occupied setpoint or the unoccupied setpoint will be used 
by the PID cell. This cell reads in values for both set-
points, chooses the one to use based on the value of an 
Occupancy input, and sends the appropriate setpoint value 
to the next cell in line, the Setpt Float cell.

 Step 2: Setpt Float - The Setpt Float cell allows alter-

ation of the control setpoint provided by the Select cell 
based on comparison of a “float” input to a range of val-
ues. The floating setpoint is then sent to the next cell in 
line, the PID Control cell.

This cell makes the PID percentage calculation based 

on the value of the setpoint (received from the Setpt Float 
cell) compared to the control input, which is fed directly 
into the PID Control cell. The resulting percentage is sent 
to the next cell in line, the Filter cell.

Step 4: Filter - The Filter cell limits the rate of change 

of the PID percentage over time, and is typically used to 
keep the PID cell from over-compensating when inputs