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sticking contacts on a safety relay

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    #16
    Sticking Contacts* Safety Relay

    Allen Bradley SLC 500 (also verbally known as Slick 500') seems to me 1990's, process control and we used them for the then HART ( highway addressable remote transmitter) interface mainly where the analog signal conductors could be used for communications, and hot swapable I/O.

    They are versatile before 'field bus' technology but were stalwart PLC with 32 bit I/O, could be programmed as 1/2 rack if desired and the back plane had these little yellow plastic inserts for the back plane of the bus in the rack(s).

    The above background since I am getting in here late. The slick controller was not redundant logic solver capabilities but could have features set up for back up and lead lag functions.

    We had occasional mishaps of processors not knowing which had the latest revision of the programmed functional sequence. I am trying to recall if it was FST (function sequence table) or just the plain DB 1 or DB 0 on the 1785 com card.

    All these things as well MESG (minimum electrical safe gap) for options of using AB 700 series relays with discreet outputs from the Slick.

    If the blue hose Data Highway (com link media IS 7001) is terminated correctly and there does not exist a Allen Bradley Guard PLC ( integrated) you may need a management of change to get your PLC version corrected after checking the scan to see I think that one scans vertically so all the ESD ladder logic has to be in the first or second rung or you will get flavors of problems.

    One option you have is determine the latest update to the program then move the key switch on the controller and reload the latest version to the kernel (AKA firmware) inside the controller to set the logic controller straight which one has the lead.
    Otherwise you will need to limp along until a shutdown for that particular line can be revised with a real safety PLC such as Triconix triple redundant I/O capable PLC.

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      #17
      Another possibility hovers on the fringe Allen Bradley around that time frame allowed block transfer of addresses from one part of the plant to another say feed forward dynamic transfer during request from one processor to another in the network. It was intended as a precursor to ENET (thinner skinny brown or beige twinaxial media) where say distilling process values were need in dehydration. Occasionally these process requirements never made a smooth transition Like ENET over IP networks.

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        #18
        Absolute gibberish. The Slick never had hot-swappable IO. If you pull an IO card out of a rack the processor faults.

        The slick and the PLC5 both had redundant systems available. AB took it off the market after the control logic redundancy system became available.

        What you are referring to as far as half rack addressing those never applied to the SLC line. It only applied to PLC 5.
        Bob

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          #19
          I thought half racks were one card rack divided into and addressed as two racks with one processor.
          The hot swappable must have been the PLC5.

          It was quite some time ago 27 years so I kind of following the idea that the SLC was not a safety PLC mentioned previouly but very nice features useful for the time of popularity. Obvious the Contrologix and Micro Logic might be fundamentally a better choice due to an out dated SLC 500 PLC.

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            #20
            SLC 500 Fault 1F51h on swap

            Evidently the SLC you could goto the Processor status file , to the IO tab, and put a zero on the IO slot enables now you can pull it out of chassis without going into a fault. if the processor processor is still in run mode when we put in the module an seat it even with the slot disabled we always got the stuck runtime error and that was what I thopught you were saying a few post back about it would report stuck.

            I just thought with the runtime error might get cleared with or fixed by a fault routine.

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              #21
              I believe the error was in the safety relay, not the PLC. Maybe your point was that an error on the PLC program is what was triggering the error in the safety relay, and that may be something worth looking into. As far as I knew, the SLCs never had a qualified Safety PLC format, so it's entirely possible that there could be something that doesn't happen correctly inside the PLC that is then triggering the safety relay, then in the process of cycling power every time to clear it, the safety relay eventually gets its own internal failure and has to be replaced.
              __________________________________________________ ____________________________
              Many people are shocked when they discover I am not a good electrician...

              I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

              Comment


                #22
                Jaref yes exactly as you surmise.

                Candidly there are theory that the back mounting plate when it is not stainless steel it can get magnetized if it is one in a large relay cabinet and the inductance of many coils in there causes or proximate distance to magnetized coil adjacent to some other ones that is why I mentioned min separation clearance between electrically pilot coils in close proximity and or the back plate.
                I kind of do follow your post occasionally so I thought oh well explain about getting in late to this thread.

                Comment


                  #23
                  Originally posted by nec_addicted View Post
                  One option you have is determine the latest update to the program then move the key switch on the controller and reload the latest version to the kernel (AKA firmware) inside the controller to set the logic controller straight which one has the lead.
                  Couple slides supporting the bench diagnostics before attempting and chnages
                  Attached Files

                  Comment


                    #24
                    Originally posted by nec_addicted View Post
                    Jaref yes exactly as you surmise.

                    Candidly there are theory that the back mounting plate when it is not stainless steel it can get magnetized if it is one in a large relay cabinet and the inductance of many coils in there causes or proximate distance to magnetized coil adjacent to some other ones that is why I mentioned min separation clearance between electrically pilot coils in close proximity and or the back plate.
                    I kind of do follow your post occasionally so I thought oh well explain about getting in late to this thread.
                    I'm calling BS on this.
                    If Billy Idol is on your playlist go reevaluate your life.

                    Comment


                      #25
                      Magnetized Rail Road Electric Relays

                      I always HAVE admired your statutory sign-off line "if you dance with a gorilla......"

                      Comment


                        #26
                        Magnetized Rail Road Electric Relays

                        I have allways liked your stautory sign off line "If you dance with a gorilla......"

                        Railroad Traffic Control and relays...

                        www.railroadsignals.us/support/relays


                        sometimes the truth is harder to believe and sounds more fantastic to comprehend than a fishing expedition.

                        My only actual experience with this type relay control phenom was a traffic control system for a bridge single lane with lights om both ends. The idea postulated was to use a relay termed for ,Tailgate logic. It was a relay that picked up back bumper when crossing past-over a coil of large conductor buried in the ground after having started on the remote end of a bridge elevated.

                        The lights worked but the reset did not. So my PLC guy in the middle of a deep sleep was called out to fix the reset from turning both lights on both ends from red to green so traffic could continue to cross.

                        cheers

                        Comment


                          #27
                          There really is a god!

                          Well the coworker paged us back to the robot cage after the brand new in the box Allen-Bradley Safety relay was just installed and low and behold what do you think happened Friday? You guessed it. The band-new-in-the-box relay that replaced the original one (to the tune of $1700 bucks for the two of them) failed on the code 11 "internal fault" after I told them all to pull up the program and find out whats latching that bit, but "NO", the co-worker didn't want to listen to me and kept listening to the robot/pallet wrapping machines tech. Now we are so far at three relays changed. First one replaced by them, now this one, and I will venture a guess they are going to tell the co-worker to replace this one to make it a grand total so far at three.

                          Yup, instead of finding the root cause of the problem we keep throwing parts at it.

                          So far, stay tuned

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