Selection, Hardware and Software Requirements of a PLC
Understand the selection, hardware and software requirements of a PLC
P1
There are 3 types of PLC, unitary, modular and rack-mounted. A unitary PLC is a stand alone unity, it has no room for expansion and works on its own. They are useful for automating activities such as stress testing. For example the stress testing of a hoist, instead of paying someone to manually control the hoists up and down movement leaving time in between each motion a PLC could be used instead. It could be set up to perform a number of cycles of movement of the hoist by the use of limit switches at the top and bottom of its movement to detect when to change direction. The time to wait between movements can be set so that the motor doesn't get strained. Other safety features could be added, for example, a set of sensors could be installed around the hoist to stop it's movement if some one comes too close to it. It would also be easier to set the parameters of the test and change them easily for testing a different hoist or piece of equipment. It would have to keep its functionality to a small scale as it can't be upgraded at all. A large variety of inputs and outputs could be used as most PLCs support analogue and digital. This would mean you could have temperature sensors in use on the analogue and through-beam sensors on digital. It is likely that this type of PLC would be mounted somewhere near the object it is controlling, most likely to a nearby wall.
A modular PLC allows for other modules to be connected to it increasing its functionality such as position sensing, stepper and servo motion control and packaging and press controls. Where it may have only had the ability to handle a certain amount of functions adding more increases this. The two or more connect together and act as if they still just one. This would be useful for a company that uses a greater amount automation than the above company, perhaps for a conveyor belt system that is wanted to be upgraded in the future
P1
There are 3 types of PLC, unitary, modular and rack-mounted. A unitary PLC is a stand alone unity, it has no room for expansion and works on its own. They are useful for automating activities such as stress testing. For example the stress testing of a hoist, instead of paying someone to manually control the hoists up and down movement leaving time in between each motion a PLC could be used instead. It could be set up to perform a number of cycles of movement of the hoist by the use of limit switches at the top and bottom of its movement to detect when to change direction. The time to wait between movements can be set so that the motor doesn't get strained. Other safety features could be added, for example, a set of sensors could be installed around the hoist to stop it's movement if some one comes too close to it. It would also be easier to set the parameters of the test and change them easily for testing a different hoist or piece of equipment. It would have to keep its functionality to a small scale as it can't be upgraded at all. A large variety of inputs and outputs could be used as most PLCs support analogue and digital. This would mean you could have temperature sensors in use on the analogue and through-beam sensors on digital. It is likely that this type of PLC would be mounted somewhere near the object it is controlling, most likely to a nearby wall.
A modular PLC allows for other modules to be connected to it increasing its functionality such as position sensing, stepper and servo motion control and packaging and press controls. Where it may have only had the ability to handle a certain amount of functions adding more increases this. The two or more connect together and act as if they still just one. This would be useful for a company that uses a greater amount automation than the above company, perhaps for a conveyor belt system that is wanted to be upgraded in the future