BobLfoot

PLC Law

166 posts in this topic

Was that Siemens TIA Portal or Siemens TIA AWFUL?
1 person likes this

Share this post


Link to post
Share on other sites
Sorry, it should be "Siemens TIA Portal" . No other software will make me to swear like a soldier

Share this post


Link to post
Share on other sites
I swear like a "sailor" [much worse than a soldier] anytime I have to use that ghastly mess of a TIA Portal.

Share this post


Link to post
Share on other sites
Program complexity grows until it exceeds the capability of the programmer to maintain it. I used to swear like a sailor when using TIA Portal V11 and V12. With V13 is it only like a soldier. Never comment a program. If it was hard to write, it should be hard to read.
1 person likes this

Share this post


Link to post
Share on other sites
So true, I couldn't help but laugh. Gets me all the time

Share this post


Link to post
Share on other sites

Ok -- I bit the bullet and edited a new edition finally [2016 Edition].  It is with the proof readers now and hopefully will be available in the downloads section in a week or so.  thanks gleblanc, RussB and JordanCClark for your assist.

Share this post


Link to post
Share on other sites

It is out and in the downloads sections.  The "official 2016 - 10 year anniversary edition" of the PLC Laws.  Enjoy and chuckle.

 

 

1 person likes this

Share this post


Link to post
Share on other sites

13221013_915055198562496_1538950842050135206_n.jpg

IF YOU ONLY FOCUS ON THE PROBLEM

 

YOU WILL NEVER SEE THE SOLUTION

Edited by Bryll
3 people like this

Share this post


Link to post
Share on other sites
On 11/8/2006 at 10:52 AM, BobLfoot said:

PLC Law #18.2: American Money says "In God we Trust" - with PLC's all others bring relevant data.

maybe the correct peripherals too.

1 person likes this

Share this post


Link to post
Share on other sites
On 11/6/2006 at 7:25 AM, ssommers said:

Yes, I know... I'm the woman who has to find & keep copies of the manual that the men never read. <g, d & r!>

I read manuals until I know them.

Share this post


Link to post
Share on other sites

I've always prepared myself everyday like this: On any given service call, expect a punch list of issues from the past 20 years.

1 person likes this

Share this post


Link to post
Share on other sites

(PLC Law 7.2) Just because a Cable fits(or someone makes it fit) the port, doesn't mean it is the right cable for the application.  ie.  DH-485 in RJ-45 ethernet port.  Mitsubishi FX-series serial 232 in AB DH+ port.  (Trust me, it happens)

Edited by Twigums
1 person likes this

Share this post


Link to post
Share on other sites
29 minutes ago, Twigums said:

(PLC Law 7.2) Just because a Cable fits(or someone makes it fit) the port, doesn't mean it is the right cable for the application.  ie.  DH-485 in RJ-45 ethernet port.  Mitsubishi A-series serial 232 in AB DH+ port.  (Trust me, it happens)

...or the other way 'round: plug in Ethernet cable to DH-485 port.

 

RS-232 cable to Profibus port...

When that didn't work, they tried adding a null modem adapter, which they forgot to remove from the front of the processor...

The processor is down low in the cabinet and not easy to see, so the next person to connect (yours truly...) didn't see the null modem adapter and plugged in the PC adapter, which instantly fried the PC adapter. The $500+ PC adapter became a paper weight.

Sigh...

1 person likes this

Share this post


Link to post
Share on other sites

Note sure this one has been covered, if so I apologize.

Dear Service Tech: If you add a wire to the control panel in an poor attempt to overcome what you think is a faulty relay, sensor, fuse holder...yes, you must put a label on it, at both ends.  You must red line and update the drawing package.  That way when I get called, I can actually fix the problem correctly.  And while you're at it, could you please put all the wiring back in the wire duct and reattach the cover?

Share this post


Link to post
Share on other sites

I just found this. It's interesting how many machine programmers there are here. I don't think I can add new laws... maybe this one Law #xxx The Allen Bradley SLC to CLX conversion software is the spawn of Satan. Don't use that thing on your poor customers hardware. Figure out the IO and write the program.

but I do have a few stories

At least 7 years ago an engineer friend called for some help. His plant, an amine treater, was down and had been down for two weeks. Two different companies came from Salt Lake City, the plant was outside of the Rifle, CO. Like really outside. They couldn't figure out what was wrong. He was $5k down for their cost and whatever the treater being offline cost them in production. I wasn't too busy and I had just come off of a startup so I was ready for some R&R. I told him that I would drive up and take a look and then go to Moab or maybe Yellowstone afterward, and only charge one way mileage and time to get there (plus hotel). I got there as a blizzard was "arriving" and by 4:30am there was 8" of snow on the ground and his foreman let me know that the only access to the plant was by snowmobile so we would have to wait. I visited Moab on that day. The next day was worse due to an additional 6" of snow. Dinosaur NP was pretty cool. The third day was better but it was 8 miles of 4WD hell to get in. After a couple of hours of almost not making it we arrived and the foreman showed me the PLC panel (SLC 500), I opened the door, plugged in, turned the key to run :-0, clicked run and the alarm horns came on. Someone had put the key in program mode. I stuck around for a second day and added some conveniences for them. They thought I was a genius lol

An electrician was adding a cooling system to a panel a few years ago and the station tripped off. They called me but I couldn't remote in. I drove two hours (the electricians were long gone) and when I got there I found a 4" diameter hole in the side of the panel, not covered btw. They never considered that there was a Control Logix  PLC on the other side. In that case he just sawed off the key even with the face of the PLC and it somehow turned to program mode. 

Same electrician... we were installing an HMI in a panel for the company that bought our site (We used a remote scada system to operate and our HMI was in the control building that was going away). I watched the same electrician drill a pilot hole with the door open (good thing) but when I came back he had a Sawzall blade pushed through the hole and was sawing away at it with the door closed. I walked over, expecting (hoping actually) the blade to be short, and suggested that he try a new blade. He pulled the new 6" blade that he had just switched to out of the saw cut ;-) and announced that it was a new blade... well S... it was 6pm on Friday and no prayer of finding another whatever he had cut into... opened the panel and it was a Din rail mounted 24VDC power supply. He had made it 1/2 way through it. His only comment? I thought I heard something pop. We had a spare in one of the other control panels in the building.

2 people like this

Share this post


Link to post
Share on other sites

I realise this hasn't had any additions for a while. But I thought I would throw in a couple that I use, now that I have had a good chuckle courtesy of everyone else that has posted in here over the years.

PLC Rule #63: When tracking down which piece of hardware is causing that really annoying, intermittent problem (which, as we all know, everyone else will be blaming on the programming), don't assume that it is only one piece of hardware. While it is rare, be open to the possibility that multiple parts are faulty. Or the possibility that the problem might have more than one cause.

PLC Rule #63.1: If your digital field inputs are causing problems with your programming, even though every other instance of that code is working perfectly, make sure the electrician (or apprentice) wired the field sensor correctly (ie. normally open or normally closed).......

 

I know Rule 63 doesn't happen very often, but it can happen. I was commissioning a plant that had the VSD's and an Omron Coupler on an EtherCAT network. Worked fine for a couple months. Then the coupler randomly started dropping out. VSD's started dropping out at the same time. And the system wouldn't reset itself without a power cycle. For those unfamiliar with EtherCAT, typically when the device comes back online, it just reconnects, the PLC doesn't need a power cycle.

After about 3 days of frustration (because it only happened randomly, so wasting a lot of time standing around trying to make it fault), it ended up being a faulty VSD comms card and a faulty EtherCAT junction. Eliminating only one of the problem parts didn't solve the problem.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now