P1-M622-16DR Mini PLC – Contact and Coil Instructions!

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Contact and coil instructions are in
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every PLC program. The Productivity
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Suite software comprises more than 82
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instructions organized into 13
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categories for the PLC.
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Contacts and coils are two of those
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categories. Contact instructions include
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NO, NC, NO edge, NC edge, and compare.
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Coil instructions include out, set,
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reset, or out flasher, debounce, timed,
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toggle, program end, and no operation.
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We will be looking at these instructions
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in the Productivity mini PLC P1M6-22
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or 16DR. We will also look at how to
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organize your frequently used
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instructions using the favorites
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feature.
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Throughout this post, we will tie each
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instruction back to our start-stop motor
0:45
circuit so you can see exactly how they
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apply to real programs.
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Let's get started. Detailed information
0:51
contained in this video can be found at
0:52
accautomation.ca.
0:55
A link has been put in the description
0:57
below. The website offers extensive
0:58
links, references, and coding samples,
1:00
making it a one-stop shop for all your
1:02
automation queries.
1:03
Once again, that is accautomation.ca.
1:09
Favorites, contact, and coil
1:11
instructions.
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The favorites section is a heading found
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under the instructions window of the
1:16
Productivity Suite software.
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You can open the instructions window by
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clicking on it in the application tools
1:21
panel or use the main menu, tools,
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instructions list.
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Right clicking any instruction in the
1:32
list opens a menu that lets you add to
1:34
favorites. Click that option and the
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instruction will now appear under your
1:38
favorites heading at the top of the
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list.
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To remove an instruction from your
1:42
favorites, right click on it under the
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favorites heading and select remove from
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favorites.
1:47
Favorites are a great way to separate
1:48
the instructions you use most often from
1:50
the full list. As you work through this
1:52
series and build more complex programs,
1:54
you will find yourself reaching for the
1:55
same handful of instructions repeatedly.
1:58
Adding them to favorites saves time and
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keeps your workflow organized.
2:05
Contacts, contact and coil instructions.
2:09
Contacts are the input conditions of a
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rung. They represent the state of
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boolean tags, physical inputs, outputs,
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or internal bits, [music] and control
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whether power flows through the rung to
2:18
the output coil.
2:20
The PLC evaluates logic from left to
2:22
right, top to bottom on each scan. For a
2:24
deeper understanding of how the PLC scan
2:26
works, see this post, understanding the
2:28
PLC program scan.
2:31
NO contact, NO, the normally open
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contact enables power flow in a rung
2:35
when the contact is energized.
2:37
It disables power flow when the contact
2:39
is de-energized. This is the most common
2:41
contact in PLC programming. In our
2:43
start-stop motor circuit, the start
2:45
input DI0.1.1.1
2:48
uses an NO contact. When the physical
2:50
start push button is pressed, the
2:51
contact energizes and power flows
2:53
through the rung.
2:55
When the button is released, the contact
2:56
opens, but the sealing contact DO0.1.1.1
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in the parallel branch keeps the rung
3:02
energized.
3:05
NC contact, NC, [music] the normally
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closed contact enables power flow in a
3:09
rung when the contact is de-energized.
3:12
It disables power flow when the contact
3:14
is energized. This is where most people
3:16
get confused. Just think of a normally
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closed contact as the opposite logic.
3:20
In our start-stop motor circuit, the
3:21
stop input DI0.1.1.2
3:24
uses an NO contact in the ladder. As we
3:27
covered in the online editing and
3:28
fail-safe wiring post, the physical stop
3:30
button is wired normally closed to the
3:32
input, meaning the input is energized on
3:35
or one in its normal state. An NO
3:37
contact in the ladder therefore passes
3:39
power continuously as long as the stop
3:42
button is not pressed.
3:44
When the stop button is pressed, the
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physical NC contact opens, the input
3:48
drops to off, and the NO ladder contact
3:51
opens, breaking the rung.
3:54
This is the correct fail-safe approach.
3:56
A broken wire or failed button
3:57
de-energizes the input and stops the
3:59
motor automatically.
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NO edge contact, NOE. The normally open
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edge contact acts as a one-shot input on
4:08
either the rising edge or falling edge
4:10
of a signal.
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It allows power flow for exactly one
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scan when the contact transitions from
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de-energized to energized, rising edge,
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or energized to de-energized, falling
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edge.
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This is sometimes referred to as a
4:22
one-shot in PLC programming. It is
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extremely useful when you need an action
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to happen only once per button press.
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For example, incrementing a counter each
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time a button is pressed rather than
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once per scan while it is held.
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See this post for more details on
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one-shot logic, how to make a one-shot
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in the PLC.
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NC edge contact, NCE. The normally
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closed edge contact also acts as a
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one-shot, but triggers on the transition
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of a normally closed contact.
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It allows power flow for one scan when
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the contact transitions from energized
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to de-energized, rising edge, or
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de-energized to energized, falling edge.
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Compare contact, CMP. This input contact
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compares two numerical values. Based on
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the selected operand, equal to, not
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equal to, greater than, less than,
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greater than or equal to, or less than
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or equal to, it either enables or
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disables power flow in the rung.
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A practical example, if you have an
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analog temperature sensor reading into
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the P1M622
5:21
16DR via an expansion module, you could
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use a compare contact to turn on a
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cooling fan output when the temperature
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tag exceeds a set point. The compare
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contact makes numeric decisions directly
5:32
in your ladder logic without requiring a
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separate math instruction.
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Coils, contact and coil instructions.
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Coils are the output elements of a rung.
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When the rung conditions, contacts,
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evaluate to true, the coil executes its
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function.
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The type of coil determines exactly what
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that function is.
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Out coil out provides an output that
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directly responds to the current state
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of the rung. When the rung is true, the
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output is on. When the rung is false,
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the output is off. This is the coil we
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have been using throughout this series
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for the motor output DO0.1.1.1
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in our start-stop circuit.
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The out coil also has a one-shot option,
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which turns the output on for just one
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scan during the transition from off to
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on.
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Set coil, set, sets the output into a
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latched on condition when the rung is
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enabled. Once set, the output remains on
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even if the rung condition goes false.
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Reset coil, RST, resets, unlatches, the
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output of a corresponding set coil. The
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output turns off when the reset rung is
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enabled.
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The set and reset instructions work
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together and are an alternative way to
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build a start-stop circuit. Rather than
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using a ceiling contact with an out coil
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as we did in our first program, you can
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use a set coil on the start rung and a
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reset coil on the stop rung.
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Both approaches produce the same result.
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The set-reset method can sometimes make
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the logic easier to read in programs
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with many interlocks.
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See our first program post for the
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ceiling contact approach, P1M622 16DR
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mini PLC first program start-stop motor
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circuit.
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Or out, OR, allows an out coil with the
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same tag to be used in multiple rungs.
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When any rung with that tag is true, the
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output turns on.
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Note, while the OR out instruction is
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available, [music] having the same
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output tag controlled from multiple
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rungs can make troubleshooting
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difficult.
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From my experience in the field, this
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should be avoided in most cases. Keep
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your outputs in a single rung where
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possible. It makes maintenance and
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troubleshooting much faster.
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Flasher, FLS, cycles an output bit on
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and off at a programmed rate. You set
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the cycle time in milliseconds.
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When the rung condition is true, the
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output will be on for half the cycle
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time and off for the other half.
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For example, setting the cycle time to
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1,000 milliseconds results in an output
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that flashes 0.5 seconds on and 0.5
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seconds off.
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A practical use of the P1M622-16DR would
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be to flash an indicator light wired to
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one of the eight relay outputs to signal
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an alarm or a mode change
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without needing a timer instruction to
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manage timing manually.
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Debounce coil, DBN, eliminates output
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coil chatter caused by rapid on-off
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transitions at the rung condition.
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The rung condition must remain
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continuously on or off for the program
8:21
debounce time before the output
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activates or deactivates.
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Chatter occurs when logic allows a rapid
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oscillation. For example, if a compare
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contact is evaluating a value that is
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bouncing just above and below the
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comparison threshold.
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In our example, the rung condition must
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remain stable for 1,000 milliseconds, 1
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second, before the output changes state.
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This adds a deliberate delay that
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filters out noise without needing a
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separate timer.
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Timed coil, TMC, holds the state of the
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output on for a predetermined time after
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the rung becomes true.
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Even if the rung condition goes false
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before the time expires, the output will
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remain on until the time duration
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completes.
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An output maintained option is also
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available, which keeps the output on
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after the time period as long as the
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rung condition remains true.
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A practical example, pressing a
9:11
momentary push button could trigger the
9:13
time coil to hold a solenoid valve open
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for exactly 5 seconds, regardless of how
9:17
briefly the button was pressed.
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Toggle coil, TGC, changes the state of
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the output each time the rung is
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enabled. If the output is currently on,
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it turns off.
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If it is currently off, it turns on.
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This is sometimes called a flip-flop
9:31
circuit. In our example, when the input
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transitions from off to on, the output
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toggles.
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This is useful for applications where a
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single push button needs to act as both
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an on and off control, common in simple
9:42
lighting or fan controls. See this post
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for the logic behind the flip-flop
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circuit, creating a flip-flop circuit in
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the PLC.
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No operation coil, NOP, indicates that
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the rung will have no operation. It is
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used as a placeholder in ladder logic,
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for example, when you are reserving a
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rung for future expansion or temporarily
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disabling a rung during development
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without deleting it.
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Program end coil, END, marks the end of
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a task. The Productivity Suite software
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automatically places an end coil at the
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end of your program.
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The PLC will execute all rungs up to the
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end coil on each scan, then restart the
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scan from the top.
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If you are enjoying this video, please
10:24
hit the like button below.
10:26
Keeping up with all the latest
10:27
automation innovations can be difficult,
10:28
[music] so hit the subscribe button.
10:31
Remember to hit the bell beside your
10:32
subscription to receive the
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notifications.
10:35
Applying [snorts] what we've learned to
10:36
our start-stop circuit.
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Looking back at the start-stop motor
10:41
circuit we have built throughout this
10:42
series, you can now identify every
10:44
instruction by name. DI0.1.1.1,
10:48
start, NO contact, passes power when the
10:51
start button is pressed.
10:54
DI0.1.1.2,
10:55
stop, NC contact, passes power at all
10:58
times, opens when the stop button signal
11:01
is energized.
11:02
DO0.1.1.1,
11:04
motor sealing branch, NO contact,
11:07
holds the rung energized after the start
11:08
button is released.
11:10
DO0.1.1.1,
11:12
motor out coil, turns the relay output
11:15
on when the rung is true.
11:17
That single rung uses three of the
11:19
contact and coil instructions covered in
11:21
this post. As we build more complex
11:23
programs in the coming post, adding
11:25
timers, counters, and math, you will see
11:27
all of these instructions combined in
11:29
increasingly practical ways.
11:32
Next time, we will look at timer
11:34
instructions in the Productivity Mini
11:35
PLC P1 M622-16DR.
11:39
Many PLC manufacturers offer a range of
11:41
hardware and software.
11:43
All programmable logic controllers share
11:44
similar basic features.
11:47
To see how I would approach learning
11:48
about basic PLCs, click here.
11:51
Click here to see how you can program
11:53
for free with the ACC PLC simulator with
11:55
3D scenes you can program.

P1-M622-16DR Mini PLC – Contact and Coil Instructions!

accautomation.ca

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P1-M622-16DR Mini PLC – Contact and Coil Instructions!

accautomation.ca