Controllers were built for specific purposes and could not be altered easily.
Early analog process controllers had to be rewired to be reprogrammed.
This controllers do what they are designed and built to do, quickly and precisely perhaps, but with little adaptability for change (beyond minor adjustments).
Modification of hard automation is time-consuming and expensive, since modifications can only be performed while the equipment sits idle.
Soft Automation
Soft Automation
Modern digital computers are reprogrammable.
It is even possible to reprogram them and test the changes while they work.
Even if hardware changes are required to a soft automation system, the lost time during changeover is less than for hard automation
Automated Mfg. System can be classified into three basic types:
Automated Mfg. System can be classified into three basic types:
Fixed Automation
A system which the sequence of processing (or assembly) operations is fixed by the equipment configurations.
Each operations in the sequence is usually simple.
