RLL Design and Sequencing System Overview

 
Chapter 7
 
 RLL Design and Sequencing System
1
 
Chapter 7: RLL Design and
Sequencing System - IE337
 
Common industrial sequences
 
A Sequential system is based:
Either on a single path sequence of tasks
Or on multi-paths
In a single path system, tasks are
performed sequentially, one after another
In a Multi-path or parallel system,  several
tasks can be performed simultaneously in
parallel
 
Chapter 7: RLL Design and
Sequencing System - IE337
2
 
Common industrial sequences
 
Chapter 7: RLL Design and
Sequencing System - IE337
3
 
Control signals
 
Depending on the controlled system, control signals can be 
either
sustain
 or 
non-sustain.
 
Chapter 7: RLL Design and
Sequencing System - IE337
4
 
Non-sustain control signal:
There is a mechanical memory.
 
Sustain control signal:
There is no mechanical memory.
 
Sequence charts
 
To visualize the operation of switching systems,
we use sequence charts, also called:
Time-motion diagrams
State diagram
Bar charts
 
They describe the step-by-step operation of sequential
systems
 
They are helpful to design RLL
 
 
Chapter 7: RLL Design and
Sequencing System - IE337
5
6
 
Chapter 7: RLL Design and
Sequencing System - IE337
 
 7.2 
Design Using Sequencing Chart
 
Flip flop module
 
Output module
 
Sequencing chart
 
CASCADE method
 
The CASCADE method is a 
method to design RLL.
 
This technique can be used to control the sequence of
operations of a machine/process having either sustain or
non-sustain control signals.
 
 
Chapter 7: RLL Design and
Sequencing System - IE337
7
 
RLL Design for non sustain
control signals
 
Chapter 7: RLL Design and
Sequencing System - IE337
8
 
RLL Design for non sustain
control signals
 
Use the CASCADE method to design an RLL for a single-path machine
sequence and non-sustain control signals:
 
Chapter 7: RLL Design and
Sequencing System - IE337
9
 
RLL Design for sustain control
signals
 
Use the CASCADE method to design an RLL for a single-path machine
sequence and sustain control signals:
 
Chapter 7: RLL Design and
Sequencing System - IE337
10
11
 
Chapter 7: RLL Design and
Sequencing System - IE337
 
RLL Design for sustain control
signals
12
 
Chapter 7: RLL Design and
Sequencing System - IE337
 
 7.3 RLL Design for Sequencing System Using CASCADE Methods
 
Multi path/parallel path
machine sequence
 
In multi-path sequences,
the program proceeds as
regular single path up to
the completion of 
step(i).
At 
step(i)
, 2 parallel
paths 
A
 and 
B
 are carried
out simultaneously.
Path 
A
 has 
j
 steps, and
path 
B 
has 
k
 steps; the 
j
and 
k
 are not necessarily
equal.
Only after completing
both paths sequentially,
the program continues
with the next single-path
step(i+1)
.
 
Chapter 7: RLL Design and
Sequencing System - IE337
13
 
Example
 
Chapter 7: RLL Design and
Sequencing System - IE337
14
 
Multi path with
Non sustain control signal
 
Path selection
 
Chapter 7: RLL Design and
Sequencing System - IE337
15
 
Some machine
sequences require
selection of 1 path
among many paths
available
Each available path is a
sequence.
A path can be enabled
using external switches.
After step(i) is
completed, either flip-
flop YA1 or YB1 is set,
depending on whether
xp = 1 or 0, respectively.
Completion of either
step Aj or Bk sets flip-
flop Yi+1
 
Example
 
Chapter 7: RLL Design and
Sequencing System - IE337
16
 
Bypass
 
Chapter 7: RLL Design and
Sequencing System - IE337
17
 
Bypass = shortcut some
operations
 
At the completion of step
(
i
)
 
If input control signal 
x
p
 
=1,
then the system goes
through program steps
from 
A
1
 
to 
A
j 
, and
continues with step (
i+1)
.
 
If, on the other hand, 
x
p
 
= 0,
then the system jumps
directly from step 
(i)  
to
step
(i+1)
.
 
Example
 
Chapter 7: RLL Design and
Sequencing System - IE337
18
X
p
=1; ( B+, B-)
          
G2 | G3
X
p
=0; by pass
 
START
, A+ ,                                     , A- .
     
G1
  
                  G4
 
Repeat cycle
 
Chapter 7: RLL Design and
Sequencing System - IE337
19
 
A repeat cycle is a machine
sequence in which some steps
are repeated.
At the completion of step 
A
j 
, if a
selector switch 
x
p
 = 1, 
then
 
the
system will continue with step
i+1.
 
Otherwise, If 
x
p
 = 0 , 
then steps
A
1 
to 
A
J 
are repeated.
 
The cycle 
A
1 
to 
A
J 
will be
repeated indefinitely until 
x
p
 =
1
.
 
This circuit is suitable for
machine sequences to be
repeated until a desired effect is
achieved.
 
Minimum number of groups in
a repeat cycle
 
Chapter 7: RLL Design and
Sequencing System - IE337
20
 
At least 
3 
flip-flops must be
allocated for repeated
machine steps.
 
If only one or two flip-flops
were assigned for the repeated
machine steps, they will
simultaneously set and reset
and multifunction would occur.
 
If the rule to divide the
machine sequence into groups
calls for only two groups to
cover the  repeated steps, a
third ‘dummy’ group must be
added.
 
Example
 
Chapter 7: RLL Design and
Sequencing System - IE337
21
22
 
Chapter 7: RLL Design and
Sequencing System - IE337
23
 
Chapter 7: RLL Design and
Sequencing System - IE337
24
 
Chapter 7: RLL Design and
Sequencing System - IE337
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Common industrial sequences in RLL design and sequencing systems involve single path or multi-path approaches. Control signals can be sustain or non-sustain, impacting the system's memory. Sequence charts help visualize system operations, aiding in RLL design. Techniques like the CASCADE method are utilized for controlling the sequence of operations in machines. Specific design methods cater to non-sustain control signals, enhancing efficiency in single-path machine sequences.


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  1. Chapter 7 RLL Design and Sequencing System Chapter 7: RLL Design and Sequencing System - IE337 1

  2. Common industrialsequences A Sequential system is based: Either on a single path sequence of tasks Or on multi-paths In a single path system, tasks are performed sequentially, one after another In a Multi-path or parallel system, several tasks can be performed simultaneously in parallel Chapter 7: RLL Design and Sequencing System - IE337 2

  3. Common industrialsequences Chapter 7: RLL Design and Sequencing System - IE337 3

  4. Control signals Depending on the controlled system, control signals can be either sustain or non-sustain. Chapter 7: RLL Design and Sequencing System - IE337 a- a+ Non-sustain control signal: There is a mechanical memory. Sustain control signal: There is no mechanical memory. 4

  5. Sequencecharts To visualize the operation of switching systems, we use sequence charts, also called: Time-motion diagrams State diagram Bar charts Chapter 7: RLL Design and Sequencing System - IE337 They describe the step-by-step operation of sequential systems They are helpful to design RLL 5

  6. 7.2 Design Using Sequencing Chart Sequencing chart Flip flop module Chapter 7: RLL Design and Sequencing System - IE337 Output module 6

  7. CASCADE method The CASCADE method is a method to design RLL. This technique can be used to control the sequence of operations of a machine/process having either sustain or non-sustain control signals. Chapter 7: RLL Design and Sequencing System - IE337 7

  8. RLL Design for non sustain control signals Chapter 7: RLL Design and Sequencing System - IE337 8

  9. RLL Design for non sustain control signals Use the CASCADE method to design an RLL for a single-path machine sequence and non-sustain control signals: Chapter 7: RLL Design and Sequencing System - IE337 9

  10. RLL Design for sustain control signals Use the CASCADE method to design an RLL for a single-path machine sequence and sustain control signals: Chapter 7: RLL Design and Sequencing System - IE337 a- a+ 10

  11. RLL Design for sustain control signals Chapter 7: RLL Design and Sequencing System - IE337 11

  12. 7.3 RLL Design for Sequencing System Using CASCADE Methods Chapter 7: RLL Design and Sequencing System - IE337 12

  13. Multi path/parallelpath machine sequence In multi-path sequences, the program proceeds as regular single path up to the completion of step(i). At step(i), 2 parallel paths A and B are carried out simultaneously. Path A has j steps, and path B has k steps; the j and k are not necessarily equal. Only after completing both paths sequentially, the program continues with the next single-path step(i+1). Chapter 7: RLL Design and Sequencing System - IE337 13

  14. + + , A B Example Multi path with Non sustain control signal + , , , , , , . START A A A B C + C 3 G , , 1 , 2 , . 5 START G G G 4 G Chapter 7: RLL Design and Sequencing System - IE337 14

  15. Pathselection Some sequences selection of 1 path among many available Each available path is a sequence. A path can be enabled using external switches. After step(i) completed, either flip- flop YA1 or YB1 is set, depending on whether xp = 1 or 0, respectively. Completion of either step Aj or Bk sets flip- flop Yi+1 machine require paths Chapter 7: RLL Design and Sequencing System - IE337 is 15

  16. + + ( ; 1 = , , ) x B B C p + , , , , . START A A C Example + + = ( ; 0 , , ) x B C B p = ; 1 2 , 3 x G G p , , 1 G , 6 START G = ; 0 4 , 5 x G G p Chapter 7: RLL Design and Sequencing System - IE337 16

  17. Bypass Bypass = shortcut some operations At the completion of step (i) Chapter 7: RLL Design and Sequencing System - IE337 If input control signal xp=1, then the system goes through program steps from A1to Aj , and continues with step (i+1). If, on the other hand, xp= 0, then the system jumps directly from step (i) to step(i+1). 17

  18. Example Xp=1; ( B+, B-) G2 | G3 Xp=0; by pass START, A+ , , A- . G1 G4 Chapter 7: RLL Design and Sequencing System - IE337 18

  19. Repeatcycle A repeat cycle is a machine sequence in which some steps are repeated. At the completion of step Aj , if a selector switch xp = 1, thenthe system will continue with step i+1. Chapter 7: RLL Design and Sequencing System - IE337 Otherwise, If xp = 0 , then steps A1 to AJ are repeated. The cycle A1 to AJ will be repeated indefinitely until xp = 1. This circuit is suitable for machine sequences to be repeated until a desired effect is achieved. 19

  20. Minimum numberof groups in a repeatcycle At least 3 flip-flops must be allocated for repeated machine steps. If only one or two flip-flops were assigned for the repeated machine steps, they will simultaneously set and reset and multifunction would occur. Chapter 7: RLL Design and Sequencing System - IE337 If the rule to divide the machine sequence into groups calls for only two groups to cover the repeated steps, a third dummy group must be added. 20

  21. ( ( ) , + + + , ) 1 = Example , , ( , , , until ) ( . START A repeat B C B C x A p ) , , 1 , 2 , 3 4 5 START G G G G G Chapter 7: RLL Design and Sequencing System - IE337 21

  22. Chapter 7: RLL Design and Sequencing System - IE337 22

  23. Chapter 7: RLL Design and Sequencing System - IE337 23

  24. Chapter 7: RLL Design and Sequencing System - IE337 24

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