Most complex PLC program?

strantor

Member
Join Date
Sep 2010
Location
katy tx
Posts
401
What application in your experience has demanded the most complex PLC program?

I suppose I should clarify what manner "complex" I'm asking about. So a PLC with 10,000 I/O controlling a few thousand valves all in the exact same way, with the same 4 or 5 rungs of code copied/pasted a few thousand times, is not what I picture when I think of complex. When I think of complex, I picture a few thousand rungs* of (for the most part) unique code, each rung* (for the most part) having required deliberate thought by someone with vast knowledge and above average cranial processing power.

Palletizers stand out in my mind as being usually pretty complex

*rungs, may be substituted for lines of ST or whatever. Not necessarily ladder.
 
Last edited:
Palletizing is usually pretty straight forward, same logic just different heights.

A few that come to mind: a transmission test line with multiple unique test stations, a operator "guided" automotive instrument panel installation servo arm that tracked the vehicle as it started and stopped going down the line, and a robot cell that featured 5 robots that interacted together to install camshaft bearings.
 
several things come to my mind.

oem test equipment such as electric car seat testers, fatigue testers, assembly line equipment.
I did a seat track program with 10 stations that had 2400 rungs.
automotive assembly lines.

james
 
Automotive body shop.
Couple hundred PLCs, conveyors, bunch of robots, welding, riveting, material handling, different model being made on every unit, possibly over 30 models made on the same line.
Each model different robot paths parts data, options, all feed from a plant system sending list of units to make.

Add to this all the material delivered to the line, operator loading stations, safeties, over 50,000 alarms per station of which there are over 100 stations.
The look aheads and data collection for quality...

And all this making a unit every 70 to 90 seconds all day everyday sometimes 24/7.

Now develop all that machinery in a 3 to 6 months and do the install in 9 weeks.

And that's just to make the metal shell of the body.
 
I wrote one for a hybrid test cell. It allowed temperature extremes from -40 to 140 F, a de-humidifier unit with 2 burners, 4 cooling/heating valves, another climate control unit with just heat, 6 sets of fans, a pop-up cooler, heat recovery system. The temp extremes had to increment 10 degrees per hour under a 30 degree temp and 20 degrees per hour above 30 degrees. 1 main controller, 2 remote racks. Also damper controls. About 14 PID loops. Probably not too complex, but very diversified.
 
Programmed an air bag inflator line using a AB PLC-5/250 Pyramid Integrator with a VAX module. 25 pick and places, indexing conveyor, RFID tracking, 12 PanelViews, 4 welding robots and barcode readers at each station using the old RB modules.
 
dahnuguy has a good example but it is just big.
I can think of veneer lathes or lumber mills mostly because of the gearing, speed, precision, and non-linear motion. Auto factories may make many types of cars but no tree is the same.

Each car is different and has around 100 different details for each model. The data being transferred from every fixture to every robot and down the line. While looking ahead to get the next car data and the one 3 or 4 up the line to process offline sub-assemblies so they are all ready when the pallet arrives.

The shear quantity of tags and faults and feedback and data storage is amazing.

The speed and volume of information being handled is just one issue.

The fault recovery allows the line to recover from faults in less than 5 minutes on average.

The number of remote I/O and subsystems and different components all being coordinated all working at the same time is more than I have seen anywhere. More than I can imagine being used in any process.

Linear motion while picking parts from a stack or pallet or rack where each part is located by machine vision and offsets calculated on the fly and parts count to flag resupply...at hundreds of locations.

Machine vision for placing glass and roofs, laser welding while using machine vision to locate and control the weld path...Stop and think about that one for a second.

It is the magnitude of all this that becomes complex. No one part is all that bad when you zoom in.



Now imagine you are cutting 1000 trees all at once and each one fits into the next... every minute, and keep up with where each one came from and then track every piece of wood from beginning all the way to Lowe's.

Or
Receive tree... rotate tree and move one cutter into it based on a feedback loop, drop the core, open the gate...
Repeat.

As interesting as it is, I don't see a couple tuned loops in a serial process of conveyors and cutters as being terribly complex over all.

You left out car washes...
 
Palletizing is usually pretty straight forward, same logic just different heights.

I have seen machine vision palletizers that were more than just pick and place and move to next level.

Imagine picking from random parts in any orientation then sorting on the fly to determine the place location while in route to one of several locations, then stack.
 
Really nothing we do is terribly "complex" when you break it down.

o_O Dont tell anyone.... they still think im a genius

Anything with motion and speed has been the hardest to grasp just because it can be so fast you cant see it happen you just have to trust that it happened and move on. Big is also complex just because you can have so many moving parts that work together and it takes a long time to fully understand the system if you did not build it.
 
I always wanted to get the opportunity to get into the UPS air distribution center in Louisville, KY or FedEx's in Memphis, TN. I was at a hotel next to the Louisville airport and could not count the UPS jets landing there were so many, the number of daily packages would be impressive.

All those conveyors tied together with hundreds of discharge points, multi-level storage, package tracking (in, out & moves), logging, etc. Those must be some pretty complex systems.
 
I recently visited the Amazon logistics center in Barcelona, 150,000 square meters, 60,000 mobile shelves moved by 10,000 robots, countless belt conveyors,

I guess the automation would be mainly AB, the electrical cabinets only had a display that indicated the supply voltages, but without any HMI screen.
 
I have seen machine vision palletizers that were more than just pick and place and move to next level.

Imagine picking from random parts in any orientation then sorting on the fly to determine the place location while in route to one of several locations, then stack.

I have and the ability to pick randomly oriented parts off a moving conveyor has been a standard feature of robots with vision for a while now ( I just finished one last week). It's still cool to watch even after doing about a dozen of these.
 
I know it doesn't sound like it should be, but I have been writing plc and hmi programs since 1997, and this inbay automatic car wash has been by far, the most difficult piece of equipment that I have ever had to program.
I think mostly, it is because people are involved. And people do the craziest things.
 
Last edited:

Similar Topics

I have my L5K file imported into my project, and the tags I need in the "available addresses". Is there a way to access my PLC tags in a complex...
Replies
2
Views
2,910
Yes it's very legacy.. but sometimes it's necessary to use old stuff for fun.. and because it's so much cheaper. Crimson 3.0 had the ability to...
Replies
4
Views
1,573
Hello all, I am fairly new to programming HMI's and am working with Crimson 3.1 for the first time. I am trying to recreate an annunciator of...
Replies
12
Views
6,271
I have this complex code tag that returns as a string variable. For some reason it returns the two strings with a ?? between them -- not the...
Replies
2
Views
3,469
Hello, I have 6 RTUs all with the same program load. I am trying to setup my HMI with one set of data tags and one set of screens and use a...
Replies
7
Views
5,773
Back
Top Bottom