EOS ProControl 2 plus Series - Key Concepts

ProControl User’s Manual v2.2X
2 \8100\0074_1017
1.2 Key
Concepts
The following are the building blocks of any Series 2
plus
monitoring and control
system.
Inputs and
Outputs (I/O’s)
No system can be effective in the real world without communication and one of the
principal ways the ProControl communicates is by responding to information
collected by sensors and by issuing " commands# to other electronic or electrical
devices. Sensor information constitutes an Input while a " command# to another
device constitutes an Output. The Series 2
plus
works with all of the more important
types of I/O devices in general use. Appendix A demonstrates how a variety of I/O
devices are connected to the ProControl.
Digital Inputs
These inputs are designed to detect the closure of switch contacts such as those
found on float switches or overpressure sensors. They can respond to any normally
open or normally closed dry contact. The Series 2
plus
provides its own wetting
(supply) voltage of 5 volts DC for each digital input circuit. The Series 2
plus
can
respond to changes in state as fast as 4 Hz or 3 Hz (cycles per second) depending on
the model purchased. Digital inputs are " debounced# for 125 or 150 milliseconds,
respectively. This means that a switch or other input that changes state (becomes
open or closed) must stay in that state for 125 or 150 milliseconds before the Series
2
plus
will respond to the change.
Up to eight high-speed digital inputs can also be used for traditional digital (pulse-
output) flow meters. These inputs can detect signal changes at up to a 200/500 Hz
rate. All high-
speed digital inputs are " debounced# for 1250/500 microseconds.
The faster rate applies only to Type A ProControl units.
Analog Inputs
These inputs are compatible with sensors which send out a 4 - 20 milliamp (mA)
signal. Most analog sensors are available with this type of signal, examples being
pressure transducers, pH transmitters, and many flow meters. These inputs allow
the operator to read the actual " value# of a parameter, such as pressure, instead of
an on/off signal.
Digital Outputs
Digital outputs turn things like pumps, solenoid valves, and alarm lights on and off.
The Series 2
plus
digital outputs are relay outputs designed to switch small loads
directly, such as motor starters, lamps, and solenoid valves.