Why do I dedicate my efforts to this?
My professional life ended a long time ago. Today, at the age of 70, I am on the home stretch and I want to dedicate some of my scarce time to the part of my working life that attracted me the most: PLC programming.
Of course, we are talking about EasyE4, nothing to do with the big systems of today, but....
I have seen in EasyE4, a product of great utility, with easy integration in different sectors, to which resources have been dedicated for its development and that has potential to grow in performance. I like it and support it. I think I understand why it has happened at EATON, and not at SIEMENS.
To make applications at a good level, you need the right tools that allow their elaboration with the least number of instructions. With such a limited system map, there is no room for indirect addressing as such, some modules incorporate it in a basic way. In our EasyE4, we will not find indirect addressing or the input/output state table. Nor will it grow so much that it collides in performance with the next step PLCs.
As we are far from its birth, it has blurred its usefulness and to whom it was addressed. At the beginning of automation, everything was relays. Then came hardwired logic, but it was short-lived. In 1982, I started my relationship with the first IPC 90 and 300.
All programming was done in contact language (electrical simile), to understand and visually analyze the conditions not met and proceed to repair them. After those beginnings, this programming mode has continued to be maintained in all PLCs. It is definitely the basic programming mode for electricians. The wired logic evolved towards function modules.
When the conditions to act are limited to protections, pressures, levels... it is not necessary to program in contact language. The states are also displayed in the instruction list (ST). The result is better understood and easier to develop. For chain and stepper motion solutions with drives in automatic and manual modes, contacts can be used in the main program and instruction lists in user function modules.
Agustín.
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