Transcript Ladder Program Elements that deal with active/passive inputs

Ladder program elements to deal with
active high and/or active low input devices
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Pre-presentation Self Assessment Activity
Your comfort level with your
response to the following three
question assessment tool should
indicate if the presentation that
follows will increase you
knowledge base on the topic
outlined by the questions in this
tool.
Pre-presentation Self Assessment Activity
Voltage Inverting Op Amp circuit
1.
Design an instrument system that includes a programmable
controller that will include a normally closed Start Push Button
and a normally open temperature high limit sensor.
2.
Redesign your system so that the button is wired the
opposite way it was in question 1 and the senor has the
opposite activity.
3.
Write a ladder program for each of your designs.
Integrating the field devices with a programmable
controller and then creating the program that
operates the field devices is a critical task.
Input Modules
24 volts
120
volts
120 volts
48 volts
WBT-4
I-0,3
I-1,3
O-0,3
“We-build-them”
Programmable Controllers
O-1,3
Output
Modules
A cartoon of a simple Programmable
Logic Controller that has two input
modules and two output modules
Note the different voltage rating for the modules.
Other modules with different voltage rating are
available.
Integrating the field devices with a programmable
controller and then creating the program that
operates the field devices is a critical task.
Input Modules
motor
Starter
120
volts
Input devices
24 volts
To
motor
and FCE
120
volts
48 volts
120 volts
WBT-4
Output device
I-0,3
N.O.
I-1,3
“We-build-them”
Programmable Controllers
N.O.
O-0,3
O-1,3
Output
Modules
A cartoon of a simple Programmable
Logic Controller that has two input
modules and two output modules
Note the different voltage rating for the modules.
Other modules with different voltage rating are
available.
The challenge is not in attaching the wires to an assigned
address (terminal) at the appropriate module.
If this was a temperature
sense high alarm device
would it have an active
high or active low output?
To
motor
and FCE
Input Modules
motor
Starter
120
volts
Input devices
(active low)
24 volts
120
volts
48 volts
120 volts
WBT-4
24 volts
Output device
TSH
N.O.
I-0,3
I-1,3
“We-build-them”
Programmable Controllers
N.O.
O-0,3
O-1,3
Output
Modules
The important thing is to know if the
devices are wired to be active high or
active low so you can pick the proper
programming element for your ladder
program.
The challenge is not in attaching the wires to an assigned
address (terminal) at the appropriate module.
If this was a temperature
sense high alarm device
would it have an active
high or active low output?
To
motor
and FCE
Input Modules
motor
Starter
120
volts
Input devices
(active low)
24 volts
120
volts
48 volts
120 volts
WBT-4
24 volts
Output device
I-0,3
TSH
I-1,3
“We-build-them”
N.O.
Programmable Controllers
120
volts
N.O.
What about this
Start push button?
O-0,3
O-1,3
Output
Modules
The important thing is to know if the
devices are wired to be active high or
active low so you can pick the proper
programming element for your ladder
program.
The challenge is not in attaching the wires to an assigned
address (terminal) at the appropriate module.
If this was a temperature
sense high alarm device
would it have an active
high or active low output?
To
motor
and FCE
Input Modules
motor
Starter
120
volts
Input devices
(active low)
24 volts
120
volts
48 volts
120 volts
WBT-4
24 volts
Output device
I-0,3
TSH
I-1,3
“We-build-them”
N.O.
Programmable Controllers
120
volts
N.O.
Start
P.B.
(active low)
O-0,3
O-1,3
Output
Modules
The important thing is to know if the
devices are wired to be active high or
active low so you can pick the proper
programming element for your ladder
program.
The challenge is not in attaching the wires to an assigned
address (terminal) at the appropriate module.
If this was a temperature
sense high alarm device
would it have an active
high or active low output?
To
motor
and FCE
Input Modules
motor
Starter
120
volts
Input devices
(active low)
24 volts
120
volts
48 volts
120 volts
WBT-4
24 volts
Output device
I-0,3
TSH
I-1,3
“We-build-them”
N.O.
Programmable Controllers
O-0,3
O-1,3
Output
Modules
120
volts
Now lets attach the output device!
N.O.
Start
P.B.
Which output module is it attached to?
(active low)
Field Device PLC Address
Ladder Program
I-1,3
Start
P.B.
I-0,0
TSH
O-0,1
TSH Alarm
I-0,0
Start P.B.
I-1,3
Motor Start
O-0,1
Motor Starter
To
motor
and FCE
I/O Map
Input Modules
motor
Starter
O-0,1
120
volts
24 volts
(active low)
120
volts
48 volts
120 volts
WBT-4
24 volts
Output device
I-0,3
TSH
I-1,3
O-0,3
O-1,3
“We-build-them”
N.O.
Programmable Controllers
120
volts
N.O.
Start
P.B.
(active low)
Next, we will look at a few ladder
programs that interface with various active
high and active low input configurations.
Field Device PLC Address
Ladder Program
I-1,3
Start
P.B.
I-0,0
TSH
O-0,1
TSH Alarm
I-0,0
Start P.B.
I-1,3
Motor Start
O-0,1
Motor Starter
To
motor
and FCE
I/O Map
Input Modules
motor
Starter
O-0,1
The TSH alarm is now an
active high device!
120
volts
24 volts
120
volts
48 volts
120 volts
WBT-4
(active high)
Output device
I-0,3
I-1,3
O-0,3
O-1,3
TSH
“We-build-them”
N.O.
Programmable Controllers
24
volts
120
volts
N.O.
Start
P.B.
(active low)
The Start push button is
still an active low device!
Notice how this wiring of the input
devices is different than the previous
example.
The motor will not run unless the
temperature sensor is passive and someone
has pressed the start button down.
To motor
and FCE
Ladder Program
I-1,3
I-0,0
motor
O-0,1
120 V
24 volts
120 volts
Start
P.B.
I-0,3
TSH
O-0,1
N.O
.
24
volts
Notice how the program
elements are different as well.
I-1,3
O-0,3
“We-build-them”
N.O.
Notice how the wiring of the
TSH input devices are
different.
I-0,0
motor
Starter
120 V
O-0,1
(active low)
Start
P.B.
To motor
and FCE
(active low)
Ladder Program
I-1,3
O-1,3
Programmable Controllers
120
volts
Start
P.B.
48 volts
WBT-4
(active high)
TSH
Starter
TSH
24
volts
48 V
I-1,3
O-0,3
“We-build-them”
N.O.
Programmable Controllers
120
volts
N.O.
Start
P.B.
120 V
WBT-4
I-0,3
TSH
O-0,1
24 V
(active low)
O-1,3
Ladder Program
I-1,3
I-0,0
O-0,1
To
motor
and FCE
Start
P.B.
TSH
motor
Starter
O-0,1
120
volts
24 volts
120
volts
48 volts
120 volts
WBT-4
(active high)
I-0,3
I-1,3
O-0,3
O-1,3
TSH
“We-build-them”
N.O.
Programmable Controllers
24 volts
120
volts
Study this example and write the program
before you go on.
N.C.
Start
P.B.
(active high)
The motor should not run unless the
temperature sensor is passive and someone
has pressed the start button down.
Ladder Program
I-1,3
I-0,0
O-0,1
To
motor
and FCE
Start
P.B.
TSH
motor
Starter
O-0,1
120
volts
24 volts
120
volts
48 volts
120 volts
WBT-4
(active high)
I-0,3
I-1,3
O-0,3
O-1,3
TSH
“We-build-them”
N.O.
Programmable Controllers
24 volts
Now try this one.
N.C.
120
volts
Start
P.B.
(active low)
The motor should not run unless the
temperature sensor is passive and someone
has pressed the start button down.
To motor and
FCE
motor
Starter
WBT-4
(active high)
I-0,3
TSH
I-1,3
O-0,3
O-1,3
“We-build-them”
N.O.
To motor
and FCE
Programmable Controllers
24
volts
N.C
.
120
volts
motor
Starter
Start
P.B.
(active low)
WBT-4
(active high)
I-0,3
TSH
I-1,3
O-0,3
O-1,3
“We-build-them”
N.O.
Programmable Controllers
24
volts
120
volts
Notice the difference.
N.C
.
Start
P.B.
(active high)
(active high)
Ladder Program
I-1,3
I-0,0
TSH
N.O.
O-0,1
24
volts
Start
P.B.
TSH
N.C
.
O-0,1
120
volts
Start
P.B.
(active low)
Notice the difference.
(active high)
Ladder Program
I-1,3
I-0,0
TSH
N.O.
O-0,1
24
volts
Start
P.B.
120
volts
TSH
N.C
.
O-0,1
Start
P.B.
(active high)
Self assessment tool
Ladder Program
I-1,3
I-0,0
Start
P.B.
O-0,1
The motor should start on command
and stop if the temperature is to high.
Write the program for this story and
this input/output configuration.
TSH
O-0,1
To
motor
and FCE
motor
Starter
120
volts
24 volts
120
volts
48 volts
120 volts
WBT-4
(active Low)
I-0,3
I-1,3
O-0,3
O-1,3
TSH
“We-build-them”
N.C.
Programmable Controllers
24 volts
Click mouse to check your answer, if it
doesn’t agree run this presentation again.
N.C.
120
volts
Start
P.B.
(active low)
Return to start of
presentation.
Post-Presentation Self Assessment Activity
1.
Design an instrument system that includes a programmable
controller that will include a normally closed Start Push Button
To motor and
and a normally open temperature high limit sensor.
FCE
motor
Starter
WBT-4
(active high)
I-0,3
TSH
I-1,3
O-0,3
O-1,3
“We-build-them”
N.O.
Programmable Controllers
24
volts
N.C.
120
volts
2.
Start
P.B.
(active low)
Redesign your system so that the button is wired the
opposite way it was in question 1 and the sensor has the
opposite activity.
Post-Presentation Self Assessment Activity
2.
Redesign your system so that the button is wired the opposite
way it was in question 1 and the sensor has the opposite activity.
To motor and
FCE
motor
Starter
24 volts
(active low)
WBT-4
I-0,3
TSH
I-1,3
“We-build-them”
N.O.
Programmable Controllers
120 volts
N.C.
Start
P.B.
O-0,3
(active high)
O-1,3
Post-Presentation Self Assessment Activity
3.
Write a ladder program for each of your designs.
Ladder Program
I-1,3
I-0,0
O-0,1
To motor and
FCE
Start
P.B.
TSH
motor
Starter
O-0,1
WBT-4
(active high)
I-0,3
TSH
Programmable Controllers
24
volts
N.C.
Start
P.B.
O-0,3
“We-build-them”
N.O.
120
volts
I-1,3
(active low)
O-1,3
Post-Presentation Self Assessment Activity
3.
Write a ladder program for each of your designs.
Ladder Program
I-1,3
I-0,0
O-0,1
To motor and
FCE
Start
P.B.
TSH
motor
Starter
O-0,1
24 volts
(active low)
WBT-4
I-0,3
TSH
I-1,3
“We-build-them”
N.O.
Programmable Controllers
120 volts
N.C.
Start
P.B.
O-0,3
(active high)
O-1,3
End of Presentation