PLC based systems are flexible in the range of operations they can control and are easily modified, enhanced or altered, even after the system is installed. Changing the logical sequence of events in the operation of a system to adjust to changing operating conditions or adding new equipment to be controlled is usually as simple as a small amount of programming by one of our skilled technical staff.
MLEE's standard PLC control systems are based on DirectLogic PLC's. These platforms provide a number of benefits, including:
- Very stable, industry tested PLC processor
- Solid, tested ladder logic (built to be a PLC
first)
- Excellent ladder logic programming software
- Internal DC power supply
- Easily configured for the project
- Expandable for any size remediation project
- Large memory for basic data logging requirements
- Modbus communication protocol can be used
- Auto tuning PID loops
- Built in clock/calendar for data logging and alarm date stamping
- Two communication ports, which allows offsite modem plus on-site display or touch screen
- Ethernet module available
- Expansion or replacement modules almost always available for next day delivery anywhere in North America
- Our PLC control systems can be used for stand alone system control, remote system control, monitoring, reporting and datalogging.
MLEE also provides control systems based on Allen Bradley, Schneider, EOS and Siemens PLC platforms.
User Interfaces
Stand Alone Control
Our on-site user interfaces can be as simple as a two line display with
control buttons, more sophisticated such as a touch screen right on
the control panel or even use a personal computer (PC) and MLEE control
software. Any of these options can also be combined with offsite control
of the system through a modem and dial-up access.
Auto-Dial Reporting
MLEE control systems can be configured to provide instant alarm notification by EMAIL, TEXT MESSAGE, FAX or VOICE.
Remote System Control
A personal computer (PC) running MLEE control software connected either through
a modem or the internet to the on-site PLC allows you not only to see what is happening
with the system, but also to make the same changes you could if you
were right on site:
- Start and stop the system
- Reset alarms
- View the alarm history
- Start and stop individual motors
- Move motors from auto to manual
- View system data such as vacuums, levels, airflows, etc. (if the remediation system has the appropriate instrumentation and the control system is configured to allow this option)
Our control software is Windows based with an easy to use process flow diagram as the main process user interface. The following is an image of the initial dial-up screen.
Input and Output Capabilities
Input signals can be either digital or analog. A digital input signal
must be either on or off. Digital signals are received from switches
such as level, pressure, and temperature. An analog input signal is
an actual numeric value and is interpreted by the PLC. Examples of analog
input signals are pressure transducers, pH transmitters and flow meters.
Output signals can also be either digital or analog. Digital output signals turn equipment such as pumps, solenoid valves and alarm lights off or on. Analog outputs can vary over a range of values (0 to 100%) and are used to control rates or speeds.
The DirectLogic line of PLC's have excellent standard input and output capabilities and are expandable to provide almost limitless control possibilities.
|
Standard Inputs
and Outputs |
Expanded Inputs/Outputs
|
|
| DL06 |
36
|
100
|
| DL250 |
256
|
2,048
|
| DL260 |
256
|
16,384
|
Datalogging
Two remote datalog setups are available with MLEE systems, the
monthly datalog and the main datalog. With an on-site PC, the datalogging
options can be expanded to record virtually any system property that
is monitored by the system.
Monthly Datalog
The monthly datalog contains a daily record, written at midnight each
night, of the month, day, operating status (at that instant) and up
to five totalized or other values. This system will store 31 daily records.
When all 31 places have been used, the system will overwrite records
starting with the oldest information.
Main Datalog
The main datalog allows recording and download of up to 680 records
at an interval determined by the operator. Each record consists of information
such as the month and day, hour and minute, operating or alarm status
and 7-14 operating values (flowrate, vacuum, pH, pressure, etc.). The
length of time data is stored depends on the recording interval. For
example, at 15 minute intervals, seven days of information could be
recorded; at 30 minute intervals, 14 days of information would be recorded.
Once all record slots have been filled, the system will overwrite records
beginning with the oldest.
For more detailed information, please visit our technical library pages.