Interconnection of safety relays/emergency stop

[tipex 0]

I'm working on a robotcell which involves three machines and one robot. All machines have their own control cabinets provided by the manufacturer and all have their own emergency safety relays for cat 4 compliance. I need to connect all the individual emergency buttons in such a manner that I still succeed keeping it cat 4 or at least cat 3. Any rants on how to do this the best way or any objections on interconnection of the safety relays?

[Moggie 17]

If the seperate sections of the machine are "interconnected" to form one "production" line then ALL the Emergency Stop buttons must stop the entire machine/line. Connect the stop buttons to one control panel safety relays and then interface this safety relay circuit into the other control panels safety relays. Alternatively remove the existing safety relays and use a programmable safety relay, Pilz Programmable Multi for example.

[panic mode 246]

hi tipex i'm not certain on European standards but this part should be close enough anyway (most of it seam to come from Europe). 1. what do you mean by "all have their own emergency safety relays for cat 4 compliance"? do you mean each machine has ONE safety controller (or "safety relay" as many call them) and all safety of one machine goes to just one such device or there is more than one per machine? 2. do you know the difference between safety categories (at least Cat3 and cat4)? 3. are you familiar with robotic safeguarding standard and do you have up-to-date copy of it? if you don't, get one (or leave this for someone else...) 4. do you need APV? stringing all e-Stops together on one safety controller will give you Cat3 at best (this is why I asked if there is more than E-Stops in those machiens as connecting multiple devices to just one Cat4 controller will not get you Cat4 circuit). however E-Stops (and only E-Stops) are a bit different from rest of the bunch because they are manual function and rely on human reflexes etc. in other words it's not very reliable anyway (humans being weakest link). so far I have not seen many places asking for Cat4 on E-Stops (usually E-Stops are either wired for Cat1 or Cat3). It is different story if there are other safety devices (automatic) such as light curtains, laser scanners, gate switches etc. Those are not affected by human factor (intention, reflexes etc.). for Cat4 each and every one of them must have own controller (or equivalent - they can be connected to advanced multi-channel safety controller such as safety PLC or mentioned Pilz Multi which imho is excelent, flexible and inexpensive product). Cat3 and Cat4 are both redundant but only Cat4 can detect and prevent fault accumulation. this sounds similar enough but circuit complexity can be dramatically different except in trivial case (single safety device). I agree about using Pilz Multi as better choice and replacement for bunch of "safety relays". I don't like using "safety relay" because there is huge difference between actual safety relay (such as Omron G7SA or AB safety relay 700S etc.) and safety controller (such as Omron "safety relay" G9S or G9SA or Pilz Pnoz X3 etc.). Relay is just relay and it has coil and contacts (safety version has contacts linked and working together as one). safety controller is much more complex device that used to have several safety relays and nowdays it may have no relays at all (usually there is still pair of relays but only on output). if you have attended program verification (someone teaching robot must go inside cell to teach) there is few other things to consider (minimum clearances depending on robot speed T1 or T2, teach box, enable swith if there is second person etc.). only robot (and EOAT) can be enabled for teaching, rest of the cell is to be disabled (by safety circuit). for example if you have turn-table or anotehr robot or similar inside cell, you can't have them enabled since person teaching robot will be focused on one robot.