Why, oh why, Do Beginners Think PLC Inputs Are More Important Than PLC Outputs?

[daba]

Inputs - Yes : Outputs - No

This PLC can't physically control anything directly. Via comms it could, but in that case the PLC does not have total control, because the external device can override this controller. I have seen many successful projects where a PLC is employed to mimic/monitor a real-world application, and its only outputs are not physical outputs, just alarms or status data.

Inputs - No : Outputs - Yes

This PLC hasn't got a clue what is happening in the real world, so could be blindingly stacking pallets 345 high when then the maximum is 3. I have seen many successful projects where a PLC has no feedbacks, but blindly carries on changing its outputs. We have all seen such applications, and they are very common, traffic lights (without road or other sensors) is just one example.

There is no right answer to the OP's question - a PLC can be deployed in many scenarios - to state that inputs or outputs are more important is a nonsense,,,,

 

[DwSoFt]

This thread just makes me miss Lancie

 

[MorphuisOGrady]

Brilliant response Muffler Bearing.. Boom!!! End of discussion

Here's my $0.02.

At some point in our life, we are taught by another human to perform a task. Think of learning how to use a toaster.
The responsible adult is going to say
"First, take the bread out of the package"
then
"Put one slice a piece in each of these two slots"
(this is the "input")

"Pull the lever down"
(also an "input")

"Wait a minute"
and finally,
"The bread will pop out as toast"

Now, think of trying to explain the same process to a child starting with "The toast comes out up here"

 

[Pierre]

IMHO - The beginners way is just fine.


The singularity of their approach being questioned by ones who believe they are masters never ceases to amaze me.



Do not be dogmatics "a system of principles laid down by an authority,..., as incontrovertibly true".



They think out of the box for they have not yet been trapped in da box.


That is what we should learn from. That is why small children have so much easiness with computers, they do not follow rules.



The art of programming has never been link to obedience... what was the saying about professionals that built the Titanic.

 

[Vartile]

This thread just makes me miss Lancie

Is Lancie gone? I haven't been around for a few years.

 

[Steve Bailey]

When Lancie got to 10000 posts he:

1. Fell off the edge of the earth
2. Was abducted by aliens.
3. Retired from posting.
4. Vanished in a puff of logic.
5. Got stuck in an endless For/Next loop.

 

[RussB]

When Lancie got to 10000 posts he:

1. Fell off the edge of the earth
2. Was abducted by aliens.
3. Retired from posting.
4. Vanished in a puff of logic.
5. Got stuck in an endless For/Next loop.

6. Realized he was wasting time answering the same questions over and over, thus moved on to bigger and better things.

 

[geniusintraining]

Is Lancie gone? I haven't been around for a few years.

I had a email with him right before or just after his 10k and he was not feeling very good.... I hope he comes back and see how much the people liked his help, I know he had some very serious health issues he was dealing with, he got screwed on a job I think it was in Colorado and they had agent orange in the building he was working in and it went air born with him inside, the effects were not good, he also wrote about it on PLCTalk once.

On a personal side he is a Man's Man... and someone I looked up to, he truly has helped many