Johnson Controls Penn System 450 Series Technical Bulletin page 74

Term
Communications
Control Module
Control Module
x
dEP
Differential Control
Direct Acting
74
Definition
Provide network connectivity and communications with other network
devices. Depending on the control module, System 450 can connect and
communicate on RS485 Modbus networks or Ethernet networks.
Communications control modules include the C450CRN-x and
C450CEN-x models. Refer to the System 450 Series Modular Control
Systems with Communications Control Modules Technical Bulletin
(LIT-12011826) for more information.
The primary module in a System 450 control system, and sometimes the
only module in stand-alone control systems. Each System 450 control
system has only one control module, which contains the control system
processor, firmware, memory, and LCD. The control module receives the
input signals from the system sensors, and it monitors and controls all of
the system outputs, including the expansion module outputs. There are
four types of System 450 control modules: standard control modules, reset
control modules, hybrid analog output control modules, and
communications control modules. See Control Modules and User
Interface on page 10 and Repair and Ordering Information on page 62 for
more information.
In the Differential End Point (dEP
screens, select the differential value that analog output number x is driving
the controlled loop or process away from. The dEP value, along with
Differential Setpoint (dSP) value, establishes the output's proportional
control band. The dEP screen appears in the Analog Output Setup screens
(only on standard System 450 control systems) after you set up and select
the Differential Sensor (Sn-d) for the output reference. See Differential
Control on page 25 for more information.
The Differential Control feature is used to monitor and maintain a selected
difference in a condition (temperature, pressure, or humidity) between two
sensor points within a system, process, or space. See Differential Control
on page 25 for more information.
With Direct Acting proportional control, an increase in the sensor signal
results in a proportional increase of the output signal generated to the
controlled equipment and vice versa. See Direct and Reverse Control
Actions for Analog Outputs on page 20 for more information.
x
) screen in the Analog Output Setup