There are two types of mechanical design for PLC systems. A single box or cube is a small programmable controller that fits all units and interfaces into one compact housing, although additional expansion modules for inputs and outputs are usually available. The second design type the modular PLC has a chassis (also called a rack) that provides space for modules with different functions.

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in Lahore
There are two types of mechanical design for PLC systems. A single box or
cube is a small programmable controller that fits all units and interfaces
into one compact housing, although additional expansion modules for
inputs and outputs are usually available. The second design type the
modular PLC has a chassis (also called a rack) that provides space for
modules with different functions.

2. Power supply
• Such as power supply, processor, selection of I/O modules and
communication interfaces all of which can be adapted to specific
applications. Several racks can be managed by a single processor and
can have thousands of inputs and outputs. Either a special high-speed
serial I/O connection or a comparable communication method is
used, so racks can be distributed outside the processor, reducing
cabling costs for large plants.

3. Signal Devices
• There are also options for mounting I/O points directly into the
machine and using quick-disconnect cables to sensors and valves,
saving time on wiring and component replacement. Discrete (digital)
signals can only take on or off values ​​(1 or 0, true or false). Examples
of discrete signal devices include limit switches, photoelectric
sensors, and encoders. Discrete signals are sent using voltage or
current, with specific extreme ranges marked as on and off.

4. High voltage
• Analog signals can use a voltage or current that is proportional to the
size of the monitored quantity and can take any value within their
scale. Pressure, temperature, flow and mass are often represented by
analog signals. These are usually interpreted as integer values ​​with
varying ranges of precision depending on the device and the number
of bits available to store the data. The PLC would take this value and
transfer it to the required process units for the operator or program
to read.

5. Electrical motor
• Proper integration will also include filter times for noise reduction as
well as upper and lower limits for fault reporting. Current inputs are
less sensitive to electrical noise (eg from welders or electric motor
starts) than voltage inputs. Distance from the device and driver is also
an issue as the maximum travel distance of a quality. A signal can also
report if a wire is disconnected along the way as a <4mA signal would
mean an error.

6. Hardware configuration
• Some special processes must work continuously with minimal
unwanted downtime. Therefore, it is necessary to design a system
that is fault-tolerant and able to handle the process with faulty
modules. In such cases, to increase system availability in case of
hardware component failure, redundant CPUs or I/O modules with
the same functionality can be added to the hardware configuration to
avoid complete or partial process stoppage due to hardware failure.

7. Hydraulic press
• Other redundancy scenarios could relate to safety-critical processes,
for example large hydraulic presses could require both PLCs to turn on
an output before the press can start in the event that one output fails
to turn off properly. Programmable Logic Controllers are intended for
use by engineers without programming knowledge. For this reason, a
graphical programming language called Ladder Diagram (LD, LAD) was
first developed.

8. Schematic diagram
• It resembles a schematic diagram of a system built with
electromechanical relays and was adopted by many manufacturers
and later standardized in the IEC 61131-3 control system
programming standard. As of 2015, it is still widely used due to its
simplicity. As of 2015, most PLC systems comply with the IEC
standard, which defines 2 text-based programming languages:
Structured Text (ST; similar to Pascal) and Instruction List.

9. Function block Diagram
• And also 3 graphical languages: Ladder Diagram, Function Block
Diagram (FBD) and Sequential Function Diagram (SFC). Burraq
engineering solutions provides best PLC boot camp training courses in
Lahore Pakistan. Online video classes are available. The Instruction
List (IL) was deprecated in the third edition of the standard.