Software refers to the non physical parts of a computing system.  Examples are the programs which contain the instructions.  The software is written in the programming language such as VB, Java and C

Firmware is the program written on an embedded device such as a microprocessor or a microcontroller.  It controls the functioning of the microprocessor IC

It is written in the assembly level language. It is called firmware as it interfaces between the software and the hardware.

Hardware refers to the physical components of a computing system such as the processor, memory and the peripherals.

The key difference is that in a microcontroller, the memory (ROM and RAM) and the peripherals are fabricated on a single IC. A microprocessor, on the other hand, does not contain the memory and the peripherals in itself.  They are separately mounted and connected.

Microcontrollers are used for specific operations, such as to control and operate a washing machine or a traffic signal.  A microprocessor can be installed for a specific function in a larger system.  It is not designed for a single operation.

The speed of a microprocessor is above 1 GHz while the speed of the microcontroller is around 50 MHz.

Microprocessors can handle greater complexity as compared to microcontrollers.   They also use more power than microcontrollers.

Embedded Electronics, as the name suggests, refers to electronic hardware and software that is embedded or attached to the equipment being controlled.  

The component may be a robotic arm in an assembly line or a life support device in an ICU.  Today, Embedded Electronics can be found in all areas of life.  The washing machine and the refrigerator at home are also controlled by embedded electronics.

The advantages of embedded systems are their small size, low cost and power consumption and their rugged construction.  The program and the logic of machine operation can be easily modified.  The cost of embedded systems are lower as they are mass produced which reduces cost.  

Embedded systems can be built using both microprocessors and micro controllers.  Embedded systems can be used as standalone units or as part of a larger network controlling a bigger system.  

Programming Embedded Systems

Embedded systems can be programming using assembly level languages.  The assembly level languages are compiled into machine level using compilers.  The program is stored in the nonvolatile memory of the system.  Microprocessors and microcomputers will have their own programming languages specified by the manufacturers.  A good understanding of the C programming language will be useful in programming embedded systems.

Conductivity is an important parameter of industrial liquids.  Conductivity is measured for liquids almost all liquids.  The conductivity of the liquid gives an idea of the ions in the liquid.

The conductivity of a liquid is measured using special conductivity sensors.  The unit of conductivity is siemen/cm.  A siemen is 1/ohm.  The unit of conductance is sometimes referred to mho (ohm written in reverse).

The conductance is usually a very low value for conducting liquids such as water.  It will be of the order of a millionth of a siemen, in microsiemens.  Highly pure water, for instance, will have a conductivity of 1microsiemen/cm.

Measurement of conductivity
Conductivity is measured by measuring the conductivity of a liquid between two electrodes whose area and distance between each other is fixed.  This is known as a cell constant.

A cell constant of 1 implies that the electrodes will have a surface area of 1 cm2 and will be spaced 1 cm apart.

Magnetic flow meters are used to measure flow of liquids that are conductive.  Magnetic flow meters do not have to physically be in contact with the medium.

Magnetic Flow meters, or Magmeters as they are otherwise called work on the basis of Faraday's law which states that the voltage produced by a moving conductor in a magnetic field is proportional to the velocity of the conductor.

In a Magnetic flowmeter, the conductive liquid such as water is passed through a constant magnetic field.

As the conductive liquid flows between a magnetic field, a voltage is induced in direction perpendicular to the magnetic field.  This voltage is measured by a pair of probes.

The flowrate can be calculated from the voltage induced in these probes.

The magnetic field is produced by a pair of electromagnets whose polarity is constantly reversed. The reversal of polarity is essential to prevent interference due to electrochemical potentials induced where the probes come in contact with the liquid.

The voltage is proportional to the velocity of the liquid, the width of the pipe (diameter), and the magnetic field strength.