I am not trying to wing my job, I just like to hear other people's opinion on my job. Maybe other people see things I miss. I ALWAYS do my own research and do my job my way. You don't got to comment if you don't want to.
With all respect machine control has very complicated indepth strict regulations to follow and a risk assessment level to catagorise the level of safety requirements for the controls would be the first step before the question you ask can be answered, when we get questions like this without a mention of the safety level catagory and the OP is actively doing the work or looking into doing the work then it gives an impression that they are out of their comfort zone or depth, your post history gives us the impression your not just dotting the I's and crossing the T's but in fact trying to do your work with a lot of input off forums, this is not a way to run a business or do your work.
Yes we understand that with so many regulations and half been ambiguous its can mean you need to clarify what they mean hence the forum is an excellent place to do so but the nature of your questions seems to edge towards the forums doing a chunk of the design for you.
As a designer you are required when asked to show evidence that proves conformity with the EHSR.
We would need to know if the machine type is listed in the AnnexIV of the machine directive which means it is subject to tighter regulation and may even have its own dedicated standard possibly of the BS60204.
The United States uses different standards and using forums over there for advice may show a confliction with our own standards if you are geographically located over here and vice versa, I believe they use the OSHA.
In reflection of my response can you give use the nature of the machine, its SIL requirement, the nature of the existing controls and how you propose to keep this level of requirement with your alterations, if you can provide this information then I can help you as this will show me you are competent to do the work you are looking into, without it we cannot help as your SIL level will denote the design permitted for the controls, this is why I posted a link with a company that have an understanding of the requirements.
So the balls in your court so to speak.
There is nothing wrong with enthusiasm and taking on jobs where you have to learn as you do them - this is my work life but its essential you understand the basics of safety and risk assessment before hand as these will guide you as to what control set up is allowable and what is not, its not a one solution fits all industry; far from it, its a minefield of regulation, standards and requirements all tailored to different situations and with all the responsibility on your shoulders for the safety of any operator, maintenance person or generally anybody who comes into contact or is near the machine laying heavily on your fail safe (if required) design.
You can get a general background of the standard required for free in most manufacturers catalogues, Ive got several guides on my shelf right now for different sources, Rockwell Automation - Safety Products catalogue is a god place to get the general idea and can be found as a free product guide in any wholesales selling there wares.... so keep an eye out.
