Sunday, November 13, 2011

The Factors to Consider when Selecting PLC





PC based Industrial Controllers:
New Controllers in Industry are leaning in the directions of PC base. Benefits of these controllers type are that they are large for Machine Information Systems (MIS) and are exceedingly fast. The sectors of Traditional Industries are not adjusting this new platform for two main reasons: They are not encouraged that they are be unsuccessful safe. Training of all workers (mainly in big Automotive Companies) would be widespread.

Selection of PLC
The selection of PLC is decided during Finding of Fact; either during design meetings or specs of customers. Omron is the favored model of PLC that the customer chooses because they are aiming Asia and Europe.

The factors to consider when choosing a PLC:
I/O
Servos
Size of Memory
Communications
Compatibility to HMI
Format
Speed

Format of PLC
You could go away with the format of Small PLC because the count of I/O is less than 100 and you do not have servos or analog to compete with; though, from a view of learning point and being that Medium Format of PLCs are the industry work horse you will utilize a Medium Format PLC with a real of back-plain.

Speed of PLC
The speed of PLC uses to be a main concern when planning controls but does not truly affect to controls now. Nowadays PLCs are rapid enough for the majority applications with full programs scan times usually less than 4 msec. This is the scan time needed for the PLC to seem at the service and program all the Inputs/Outputs. The Cycle Time is 4 seconds so the majorities PLCs today are glowing when think this requirement of time.

Memory Size of PLC
Memory Size is the memory amount available for the code of PLC. It will be decided by the anticipated program size required for the machine and also the instructions type used in the program. The Analog and Serial Instructions, PID tends to utilize extra memory and CPU time. Generally PLCs need a Lithium battery to keep the program in memory when power is eliminated from the machine.

A lot of PLC has flash cards that can be additional to make bigger memory for Comments and Tags. The memory of Flash Card is nonvolatile and is really good to store tags and comments. The Ladder Programs of PLC do not have to be confirmed in order to create changes as the entire program with comments s and tag can be uploaded to the Personal Computer.



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