A dying technology

[dicklaxt]

The ability of complete systems to function thru the use of the hard wired logic of relays,cam switches,on/off delay relays etc,process switches going from digital to electronic analog devices..............the advent of PLC started it all maybe 35 to 40 years ago then that evolved to the more sophisticated DCS and now smart starters & relays,CNC machines, smart this and that.The use of computers to send control commands to large systems etc.

I have to agree that the new technology is better and more reliable,easier to change control logic with preprogrammed data and touch pads and probably cheaper in the long run for example how long would it take to tear down a conveyor system relay panel & rewire same after it had been re engineered and designed versus running a 30 minute program,,,,,maybe a bad example but you know what I mean.

The use of simple(todays technology comparison) relay logic is still used and will be around for years to come but designing sheet after sheet of ladder diagrams to start or shutdown complete process units or even plants was more rewarding than hitting some keys on a keyboard.They have taken the fun out of design.

Okay just a vent for today,can't take it out on the dog all the time.

dick

 

[RichB]

I resemble that rant I have had the opportunity to design and build quite a few systems over the years and I liked it. Seems like it just isn't as much fun now

If anyone is interested pm me and I'll send ya the prints for the last one I did--it's for testing data collection and ramp metering controllers for highway use--uses all the old tech(sigh ---old tech--just like me I guess)LOL

 

[GeorgeKoehl]

the good and the bad

the good and the bad

I have mixed feels about the digital controllers and relays. For all the benefits, the worst part is that all the circuit logic is hidden when you are trying to trouble shoot.

 

[SG-1]

I still think well designed electro-mechanical controls will out last a PLC. They are easier to troubleshoot & test. If one device fails you just replace it.

I do agree the PLCs are cheeper for very complicated schemes. I doubt every rung of logic is proven, contact by contact as would be done with the electro-mechanical counterpart.

 

[Strahan]

I still think well designed electro-mechanical controls will out last a PLC. They are easier to troubleshoot & test. If one device fails you just replace it.

I do agree the PLCs are cheeper for very complicated schemes. I doubt every rung of logic is proven, contact by contact as would be done with the electro-mechanical counterpart.

I'll have to disagree with that! I can connect and tell you where the problem is before you even get your meter out of its case.:grin: Do it everyday at my job. And I agree with OP unfortunately guys especially you youger folks the day will come when you either wish you knew more about this field or you are forced to know more about this field. You may even be surprised I started as an industrial electrician and worked it for years once I made the choice to be a controls guy I found the transition to be fairly easy. I also know controls guys who have no idea how to be an industrial electrician. The evolution of technology will never stop.

 

[Chev]

Until recently, safety circuits were required to be done with relays being hard wired due to the opinion that electronic safety circuits were unreliable, but the pilz relays cemented the change due to their quirks (my opinion) as sometimes to get an ok signal the power needed to be recycled. I think some plants still use this type of technology as they are afraid their electricians couldn't handle the updated technology. We're still making "new" weld tool fixtures with "old" technology.

 

[dicklaxt]

It follows:grin:, the last plant shutdown I designed was a tripple redundancy set up with 2 TDC 3000 's backing up each other with a hard wired relay scheme backing them both up.

Yes they still come into play but still are being phasing out for the most part.

dick

 

[don_resqcapt19]

With the extensive use of networked control systems and the very real possiblility of outside hacking, I trust electonic saftey circuits even less now than I did in the past.

 

[macmikeman]

The other thing is relays and contactors are not affected by electromagnetic pulse attack which is possibly in the toolbox of terror groups. However if the poco goes down due to all the electronics of the transmission control system, that is a moot point anyway...

 

[dbuckley]

The one thing that PLCs have in their favour is ease and speed of of change.

Now that may be a good thing, or it may be a bad thing

 

[don_resqcapt19]

The other thing is relays and contactors are not affected by electromagnetic pulse attack which is possibly in the toolbox of terror groups. ...

Or from the natural effect of a giant solar flare

 

[Pierre C Belarge]

With the extensive use of networked control systems and the very real possiblility of outside hacking, I trust electonic saftey circuits even less now than I did in the past.

That is an interesting point.

 

[Besoeker]

I'm an old guy but I'm comfortable with both relay logic and PLCs.
What I have seen in the transition from relay logic to PLCs is that implementation of ladder diagrams in a PLC isn't always quite "economical" or as simple as it could be. With hard wired control, each additional relay or even each contact, has a cost in terms of both hardware and the time to install and wire it up. Least complex has merits. With a PLC those same constraints don't apply. Sticking in a few extra contacts or relays adds no hardware costs and probably saves time in a design that will work. All good. But it can make subsequent fault finding and modifications more of a challenge than it need be.

I'm not a Luddite. I embrace new technology. I just like to see best use made of it.

 

[iaov]

For a lot of us old timers they have taken a bit of the joy out of electricity with the new fangled gadgets. I started my career working on tube circuits. I got a great deal of satisfaction trouble shooting down to component level. Finding that bad cap or transistor in a room full of cabinets with thousands of parts was a thrill. However as my dad always said " There are no good old days, just old days!" Everything works better and is more reliable today.

 

[hillbilly1]

I designed and built several fairly sophisticated green house controllers for a customer using relay logic. The customer was tired of being held captive by the manufacture of their old systems. My system used standard off the shelf parts. A PLC would have reduced the cabinet size greatly, but the reliability has been great. The system has been in operation for at least ten years now.