Help with Rewiring Robotic Assembly Line - Page 1
Forum section: electronics / projects

author: benwis
author_rank: Contributor
timestamp: September 09, 2017, 11:18:31 pm
content: I've inheritedresponsibility for an extremely unreliable PLC controlled conveyor system with multiple robotic workstations, and I need to get it up to par. A big part of that issue is the poorly mapped, badly maintained, inconsistent, and confusing wiring scheme. You can take a look here:http://imgur.com/a/mE9Y3I'd like to get this thing mapped, properly routed, tagged with identifiers, and properly terminated. I'm relatively new to somewhat complex wiring management. What would you guys recommend?For starters, I think I need to get it all into conduits that run along the frame, map the system and tag it with labeled heat shrink(or some other medium,) choose a better method for wire splicing, standardize on a thicker gauge stranded wire with crimped connectors for screw terminals, and try to reduce the cable crossover and number of breakout boards.What parts/techniques/resources/tools do you recommend to get this thing under control? Is there a good book/best practices guide for low voltage dc wiring of PLCs and other systems?Thanks!

author: Vtile
author_rank: Super Contributor
timestamp: September 09, 2017, 11:49:07 pm
content: That is not even a bad one.Take a whole building with a few kilometers of control cabling and lost documents as a poorly maintained situation.Your inherited rats nest looks like a typical educational institution lab equipment that have had too many cooks.I would start by reverse-engineering the schematics or if there is schematics verifying them to the current situation and marking down the cables with some temporary manner while doing it. After that you can start to think what and how you can tidy it up and make it to be better maintained.

author: benwis
author_rank: Contributor
timestamp: September 10, 2017, 12:02:30 am
content: That sounds terrible, There's quite a bit more than I took a photo of, but at least its in one room!

author: tpowell1830
author_rank: Frequent Contributor
timestamp: September 10, 2017, 01:52:51 am
content: Having been an electrician for years in the '80s, i had to deal with that situation many times. You could clean up the schematics, get them organized or re-draw into one schematic. But if your system is working, I would take those items one at a time and clean up the wiring and maybe try a little more organization to the devices. Create what I would call a 2d elevation view to show where all devices, etc. are located on the rack in a CAD drawing tool.I would clean up the wiring using something like this:http://www.graybar.com/store/en/gb/lead-free-pvc-type-f-narrow-slot-wiring-duct-92139209?cm_mmc=pla:google-_-googleshopping-_-gb5458-_-92139209&utm_source=google&utm_term=&utm_campaign=Graybar%3EPLA%3ECategory&utm_medium=cpc&utm_content=MBrMhiaG|pcrid|49843352090|pkw||pmt|&gclid=EAIaIQobChMI8o-e976Z1gIV0Zd-Ch1W1gqqEAQYBSABEgJX2PD_BwE#{Width%20(Inches):2}&{Height%20(Inches):2}&{Length:6%20ft.}&{Color:Light%20Grey}You could take it even further by replacing your wires with cables when appropriate or contiguous wire when necessary (broken, spliced strings).

author: rstofer
author_rank: Super Contributor
timestamp: September 10, 2017, 04:00:57 pm
content: My personal preference, after multiple decades of working machine controls, is to land the field cables on terminal blocks, NOT on the PLC itself. That multi-way splice then becomes a series of adjacent terminals with factory jumpers between the poles.https://www.digikey.com/product-detail/en/cinch-connectivity-solutions/140J-1/CBB313-ND/1276965This jumper is for barrier type terminal blocks, there are other solutions.I like to have Panduit above and below the field terminal blocks. So, the PLC on top, a run of Panduit, the field terminal blocks, another run of Panduit at the bottom.I don't have an issue with jacketed cable but most of the machines I wired used #14 AWG Machine Tool Wire like:https://www.alliedelec.com/carol-brand-general-cable-c2105a-21-07/70040593/Red of control, blue for DC, black for power. Real MTW will have MANY more strands of much finer wire - that #14 above has 41 strands of 30 AWG wire. Building wire will probably have only 7 strands. It matters...Cables were tagged with T&B or Brady wire markers - usually just numbers:http://www.newark.com/thomas-betts/wm-a-z/cable-id-markers/dp/46F5981There are heatshrink cable markers but they tend to be more useful for manufactured products where you need 100's of identical tags. Then there is the aircraft industry where they heat stamp the cable every 12" end to end. Very nice! When I was about 10, my dad brought home some wire with my name stamped every foot!Depending on the terminal type, crimped terminals may be required. Use a ratchet type crimping tool, not one of those "Do-All" pliers that cut, strip and do a half-assed job of crimping. 25# pull-out required on small cables.There are DIN terminal blocks that are very nice. In Europe, it is common to put a sleeve/ferrule over the wire ends rather than compressing directly to the wire.https://www.phoenixcontact.com/online/portal/pi?1dmy&urile=wcm:path:/pien/web/main/products/subcategory_pages/Terminal_blocks_P-15/4784f273-1e2b-4a34-8da7-709d3af232aahttps://www.phoenixcontact.com/online/portal/pi?1dmy&urile=wcm%3apath%3a/pien/web/main/products/subcategory_pages/Tools_P-25/8180ec6c-b52b-4694-a5a6-ec0f28558052/8180ec6c-b52b-4694-a5a6-ec0f28558052You can spend a lot of time at the Phoenix site coming up with workable terminal blocks.The Phoenix approach to jumpers:https://www.phoenixcontact.com/online/portal/pi/?uri=pxc-oc-itemdetail:pid=3030352&library=pien&pcck=P-15-07&tab=1&selectedCategory=ALLPanduit catalog:http://www.panduit.com/ccurl/446/912/industrial-electrical-solution-catalog-2016.pdfPage B1.4 has a picture of a neat installation and page C1.4 shows the DIN Rail Panduit where the terminal blocks are mounted right above the Panduit. That's a very nice installation.Of course, not all products in the catalog are available for instant delivery. A few phone calls may be required.