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PLC programming isn't hard because the
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instructions are complicated. It's hard
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because you're writing software that
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moves real motors. And the gap between
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logic on a screen and metal that can
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hurt you is where beginners get stuck.
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I've watched a lot of people take their
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first run at a PLC. Electricians, IT
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folks, maintenance techs, students, and
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they almost all hit the same walls. So,
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let's talk about the real challenges,
0:25
not the textbook list and the one free
0:27
tool that knocks most of them down at
0:29
once. Detailed information contained in
0:31
this video can be found at
0:32
accccclautomation.ca.
0:35
A link has been put in the description
0:36
below. The website offers extensive
0:39
links, references, and coding samples,
0:41
making it a one-stop shop for all your
0:43
automation queries. Once again, that is
0:48
Challenge one. It controls real
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In normal programming, a bug causes a
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window to crash. In PLC programming, a
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bug slams a cylinder home. That changes
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how you have to think. Newcomers
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underestimate how much they need to know
1:02
about the machine before they touch the
1:05
How does the sensor behave in a jam?
1:07
What happens on a power loss? Where's
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the estop in the logic? You're not
1:11
really a programmer. You're a process
1:13
person who writes logic. Safety comes
1:15
before the first rung, not after the
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machine bites someone.
1:19
Challenge two, the scan cycle.
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This is the big one. If you come from
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C++, Python, or Java, you expect code to
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run top to bottom and pause where you
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want. The PLC laughs at that. It reads
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every input, solves the whole program
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top to bottom, updates every output, and
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does it again hundreds or thousands of
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times a second. An output that won't
1:40
turn off. Two coils fighting each other.
1:42
A race condition. Almost every
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beginner's headache traces back to not
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picturing the scan cycle. And you can't
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read your way out of this one. You have
1:54
Challenge three, contacts versus coils.
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Every manufacturer has their own
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software and their own quirks. And then
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there's the language. Ladder logic is
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brilliant if you grew up with relay
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drawings, and baffling if you didn't.
2:08
Contacts are inputs. Coils are outputs.
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And a normally closed contact on the
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screen does not mean the field device is
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wired normally closed. Mixing those up
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is the most common rungle level mistake
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I see. Here's a number that surprises
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people. Even today, most installed
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systems are still running ladder logic.
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Much of it decades old. It's not going
2:28
anywhere. Make peace with thinking in
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Challenge four. Timers counters memory.
2:35
Timers and counters trip people up
2:36
constantly, usually because they're
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imagining the behavior instead of
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drawing a timing diagram. When a timer
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isn't doing what you expect, sketch the
2:44
timing diagram first, every time, and
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memory is the quiet one. Input, output,
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internal, retentive. Retentive memory
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survives a power cycle. Non-retentive
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Get that wrong and your machine
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remembers or forgets at exactly the
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Challenge five, planning first.
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The biggest time waster isn't even
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Beginners open the software and start
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dropping contacts before they understand
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Then come the endless rewrites. That's
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why I teach the five steps to PLC
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program development. Step one, define
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the task. Step two, define the inputs
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and outputs. Step three, develop the
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sequence of operation. Step four, write
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the program. Step five, test it. Notice
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that writing the program is step four.
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skip the front end and you don't save
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time. You just move it to the back end
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with interest. [music]
3:40
Challenge six, debugging live.
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Debugging a PLC means going online and
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watching the live logic light up as the
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machine runs. There's no break point
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that freezes the world. It's an
3:51
adjustment, but online monitoring is
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also the PLC's superpower.
3:56
You can literally see truth flow through
3:59
If you are enjoying this video, please
4:01
hit the like button below. Keeping up
4:03
with all the latest automation
4:05
innovations can be difficult, so hit the
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subscribe button. Remember to hit the
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bell next to your subscription to
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receive notifications.
4:13
The fix free in your browser.
4:16
Here's what all these challenges have in
4:18
common. You can't see what the program
4:19
is doing. The scan cycle is invisible.
4:23
Contacts and coils are abstract. The
4:25
timing of an output is a guess until you
4:27
watch it. That's exactly why I built the
4:29
ACC PLC simulator. It runs free right in
4:33
your browser. No software to install, no
4:35
hardware to buy, no login. You write
4:37
click style ladder logic and watch it
4:39
drive a real 3D machine. Inputs lighting
4:41
up. Coils energizing the scan solving in
4:46
Five scenes each targeting a different
4:48
challenge. Control panel for start stop
4:49
and the scan cycle. Traffic light for
4:51
time sequencing. Conveyor for sensors
4:54
and moving parts. Tank fill station for
4:56
analog and level control. And the
4:58
palletizer ties counting and sequencing
5:00
together. Try it free.
5:02
accccclautomation.ca/simulator.
5:04
Open the control panel scene. Build a
5:06
starttop circuit. Toggle the inputs and
5:08
watch the rung go true. 10 minutes there
5:11
will teach you more than an hour of
5:14
Go to accccclautomation.ca/simulator
5:17
and try it right now. It's free. None of
5:20
these challenges is a reason to quit.
5:22
They're just the things nobody tells you
5:23
on day one. Get your hands on a
5:25
simulator, plan before you program, and
5:27
respect the machine, and you'll be past
5:29
the hard part faster than you think.
5:32
If this helped, subscribe to ACC
5:34
Automation for more. And tell me in the
5:36
comments what tripped you up when you
