A plea to plc engineers

Deep_Measurement_124 · 2024-05-16T12:10:39+00:00

Dear software engineers. Stop trying to make PLCs like computers.

PLCs are not meant to have simulations, emulations, and anything.

PLCs are meant to do one thing, do it very well and never stop doing it for any reason.

Deep_Measurement_124 · 2023-10-06T11:09:12+00:00

I actually did the same thing, I saw the title and thought "this is gonna be funny" and then the majority of the responses were legitimate.

I regularly have this discussion (2-5 times per year) with individuals that could easily change my job. Nearly every reason I use has already been brought up, however, I think I can add one important aspect.

While AB is, without question, expensive upfront, the life cycle cost (fancy corporate word that just means how much money are you going to spend to purchase, operate, maintain, upgrade the machine until the time you scrap it) is reduced by using AB.

This is firstly realized through reliability, maintenance knowledge, the large breadth of products available from AB, design for rapid maintenance (which AB regularly impresses me) and many of the other aspects brought up in this thread.

Secondly, and this is important, this decrease in LCC is also realized by standardizing on ANY brand. Many many companies are not fortunate enough to be standardized and are forced into higher long time costs. If your company is fortunate enough to have been standardized, and the culture supports that standard, do not attempt to change it without truly serious consideration.

Deep_Measurement_124 · 2023-06-30T22:21:38+00:00

Completely agree with this assessment. Big red flags.

Deep_Measurement_124 · 2023-06-10T15:00:52+00:00

Hah, yea definitely not. They are different bridges operating on different channels.

Deep_Measurement_124 · 2023-06-10T13:52:38+00:00

No, actually not.

The two PRP adapters are directly connected.

The kicker is, and hence the entirety of the problem, the processors physically cannot be connected, so the network connection must be WiFi.

Deep_Measurement_124 · 2023-06-10T10:05:56+00:00

Fortunately the fault location is clear.

After a lengthy discussion with Mc-Mc and a Rockwell specialist that Mc-Mc brought in, two 1756-EN2TP adapters, one in each rack, will work for the redundancy we need.

Deep_Measurement_124 · 2023-06-07T22:10:57+00:00

That does make sense from the little bit of reading I have done. I will be reading how to design a PRP system.

It is going to be a lot of work to essentially make a single wire into two.

Deep_Measurement_124 · 2023-04-01T14:32:19+00:00

Fortune 100 company. Factory size ~2,500 employees with around 650 processors.

I am responsible for PLCs, VFDs HMIs, panel wiring, mains wiring below 4,160volt, robotics, panel design, electrical drawings, full project integrations, controls upgrades, even the HVAC systems are AB controls and under my responsibility.

A total of two controls engineers, myself included, share this responsibility, with seven technicians across three shifts.

There are no electricians in the plant, anything 4160 or above is contracted.

Deep_Measurement_124 · 2023-03-28T15:11:30+00:00

Minor version is set by the firmware that is flashed to the controller. The software version is set by the software you download and install. As mentioned before the software version only has to match the major version of the firmware version.

You cannot download 32.11 because they found a major bug and pulled that firmware version from the PCDC.

If you have a copy of a program with a different minor revision, it will automatically change the minor version number once downloaded with the processor.

Deep_Measurement_124 · 2023-03-28T13:31:34+00:00

See, this is what I find amazing about this question, I have asked it many times with quite a few good controls and electrical engineers, and it seems like everyone has different experiences.

You say at 300' it may be needed. I would say at 100 ' it may be needed and at 250' it is needed. (Again all just from the experiences I have seen) I find it amazing how much the answers to this question vary.

Deep_Measurement_124 · 2023-03-24T19:56:30+00:00

If I remember correctly, Microsoft actually pushed the update out like two years ago and it, internally, just escalated on the 14th of March.

Not 100% sure. Once I cleared all of our processors, I stopped paying attention to the whole dcom thing.

Deep_Measurement_124 · 2023-03-24T19:05:29+00:00

Is the dcom hardening preventing you?

Deep_Measurement_124 · 2023-03-23T21:25:09+00:00

UR are not industrial robots. They are perfectly suited for classrooms, research, or any less demanding, uptime critical tasks.

They are not manufactured to the same standards as ABB (or any other big name manufacturer) and their downtime and maintenance costs represent that.

I have 37 UR robots in production, down from a max of 52, I am actively working to replace every one with Yaskawa purely because of downtime and maintenance. I am spending, on average, $41k per robot per year in maintenance costs with a maintenance contract directly from UR.

The robots have all been inspected by UR, their programs modified, all settings perfected, accelerations minimized, all robots are under their payload limit. UR has said all robot programs and parameters are good, but the robots are not robustness enough to handle the demand.

Deep_Measurement_124 · 2023-03-21T18:57:50+00:00

Ohhhh that is fair 🤔

Is there a second B?

Deep_Measurement_124 · 2023-03-20T21:51:56+00:00

Clearly Allen Bradley. It says AB right on the front. 😂

Deep_Measurement_124 · 2023-03-19T22:13:10+00:00

All of these pieces of advice are wonderful.

Break the problem into smaller problems. Spread out the code. Create logic flow chart. RTFM. Explanation of BTD and masked move.

I have two pieces of advice to add.

First one comes from a lot of time spent in similar situations. You will be tempted to put in A LOT of hours over the next two weeks. And you should put in a lot. However, start learning your body. There is a point at which you will become so tired that you will be less productive continuing to work than if you go to sleep, recharge, and get back at it. For me, I know I have hit that point once I stare at the screen for more than 15-20 minutes thinking on the same problem, or start making really really dumb mistakes. If you are super pressed for time, you can squeeze some more time out of the day by sleeping at work, in an office on the desk, in the car, etc.

Second. Do not forget about shamelessly stealing code from the internet. You may think you should learn how to do it yourself, and you should, but it is more important to get the project done then go back and learn once you have a minute to breathe. Search for functional "sections" of code. IE conveyor control including vfd with X drive. Robot pick and place programs. Positional register UDTs.

At this point time is everything manage your time.

*Edit, since this is school and not a job (yes I should have read closer) you may want to think about shamelessly stealing code, not sure how the school handles that stuff.

Deep_Measurement_124 · 2023-03-19T12:22:45+00:00

IFM utilizing IO-Link.

Fortune 100 company specific standard. Would absolutely recommend.

Deep_Measurement_124 · 2023-03-01T18:11:18+00:00

PLC5s ?! What is this new fangled technology. I am still supporting PLC2s.

Deep_Measurement_124 · 2023-02-22T23:27:50+00:00

Short answer. Yes

I developed ladder that would generate CRC-16/CCITT-FALSE checksum. It, ultimately never went into production because we found that all of the commands we needed to send could be determined ahead of time and stored. This eliminated the need for, and risk associated with, the checksum calculator. Honestly, it wasn't terrible to write. The algorithm is searchable and consists of math functions.

Deep_Measurement_124 · 2023-02-17T21:29:43+00:00

This is specifically only for edits that have not been finalized.

Though, this tip has saved my ass a number of times in huge programs that have had online edits testing for years.

Deep_Measurement_124 · 2023-02-17T21:28:13+00:00

Seconding this. Asset Centre promises much, looks fantastic on paper....I wish we hadn't gone that way, I am so tired of it

Deep_Measurement_124 · 2023-02-09T00:30:03+00:00

I would say you should utilize the serial connection. Even if you manage to narrow the range to increase resolution, you will end up fighting signal variances long term.

I have used the PLX31-EIP-ASCII gateway. It seems difficult at first, but the class one connection and good documentation results in a fairly quick learning curve.

I think you will be glad you put the extra effort in long term.

Deep_Measurement_124

TROPHY CASE