Up Counter Instruction In PLC

Up Counter Description :

• Count Up Instruction Use to Increment the Value at Output CV.

• Count Up Input Changes from 0 to 1 (Positive Signal Edge) Current Counter Value Increment at Output CV.
• Counter Value Increment Each Time When Positive Signal Edge Is Detected.
• When Counter High Limit Reached, the Signal State at the CU Input no longer effect on the Count up Instruction.
• Current Counter Value is Greater than or Equal to the Value of the PV Parameter the Output Q is set to Signal State 1.
• When the Signal State at Input R Changes from 0 to 1 the Value at CV Output is Reset to Zero. 

Up Counter Parameters :

Parameter	Declaration	Data type	Description
CU	Input	BOOL	Count input
R	Input	BOOL	Reset input
PV	Input	Integers	Value at which the output Q is set.
Q	Output	BOOL	Counter status
CV	Output	Integers, CHAR, WCHAR, DATE	Current counter value

Up Counter Example :

Up Counter

• When the Signal State of the TAG_1 Changes From 0 to 1, the Count Up Instruction is executed at and the Current Counter Value of the CV Value is Incremented by one.
• Counter Value is Incremented until the High Limit of the Specified Data Type (INT= 32768) is Reached.
• When Current Counter Value is Greater than or equal to Zero the value of the PV Value Output Tag_3 Signal State 1.
• In all other cases, the Output TAG_3 has Signal State 0.
• When the Signal State at Input TAG_2 Changes from 0 to 1 the Value at CV Output is Reset to Zero.

Timer Off Delay (TOF) Timer Description

TOF Timer Description :

• TOF Timer instruction to set Time Delay resetting of the output by set PT Time of Timer. 
•  Input Changes From 0 to 1 (positive signal edge) Timer PT time Start and Output change from 0 to 1 (ON).
•  When PT Time Equal to Elapsed Time Output Change From 1 to 0 (Output OFF).
• Output Remain On as long as PT Time Running.
• When PT Time Expire Output change from 1 to 0 (Output OFF).

TOF Timer Parameters :

Parameters	Declaration	Description
IN	Input	Start input
PT	Input	Duration of the off delay
Q	Output	Output that is reset when the time PT expires
ET	Output	Current time value

TOF Timer Timing Diagram :

TOF Timer

TOF Timer Example :

• Start PB change from 0 to 1,TOF Timer Preset Time Start.
• When Start PB Changes from 0 to 1 Output Change from 0 to 1 (Motor ON).
• When PT Time Completed Motor Changes From 1 to 0 (Motor OFF).
• Motor set to on as long as PT Time Running.

Timer On Delay (TON) Timer Description

TON Timer Description :

• TON Timer instruction to set Time Delay of the output by set PT Time of Timer. 
• Input Changes From 0 to 1 (positive signal edge) Timer PT time Start.
• When PT Time Equal to Elapsed Time Output Change From 0 to 1 (Output ON).
• Output Remain On as long as Input is ON.
• When Input Change from 1 to 0 Output change from 1 to 0 (Output OFF).
• Timer Starts when new positive edge detect at input side.
• Current Time Store at ET Output.
• TON Timer Starts at Set PT Time and ends when PT Time Equal to ET Time.
•  ET Output Reset when input changes from 1 to 0.

TON Timer Parameters :

Parameters	Declaration	Description
IN	Input	Start input
PT	Input	Duration of the on-delay
Q	Output	Output that is set when the time PT expires
ET	Output	Current time value

TON Timer Timing Diagram :

TON Timer

TON Timer Example :

• Start PB change from 0 to 1 TON Timer Preset Time Start.
• When PT Time Completed Motor Changes From 0 to 1 (Motor ON).
• Motor set to on as long as Start PB ON.
• When Start PB Change from 1 to 0 Motor change from 1 to 0 (Motor OFF).

Pulse Timer Description

Pulse Timer Description :

• Pulse Timer instruction to set the output for a programmed duration.
• Input Changes From 0 to 1 (positive signal edge) PT time start when timer start.
• Output set for the duration of PT time start.
• If new positive edge detects output is not affect when PT time running.
• Current time value store at ET Output.
• Timer Starts at set PT Time and ends when the value of the time reach at PT.
• PT Time elapsed and Input Change From 0 to 1 and Output change from 1 to 0.

Pulse Timer Parameters :

Parameters	Declaration	Description
IN	Input	Start input
PT	Input	Set time value
Q	Output	Pulse output
ET	Output	Current time value

Pulse Timer Timing Diagram :

Pulse Timer

Pulse Timer Example :

• Start PB change from 0 to 1 Pulse Timer Preset Time Start and Motor Changes From 0 to 1 (Motor ON).
• Timer Current Running Time Store at the Elapse Time.
• When PT Time Completed and Motor Change From 1 to 0 (Motor OFF).

Basic Ladder Logic Instruction of a PLC

1. Bit Logic Instruction

• Normally Open (XIC)
• Normally Close (XIO)
• Positive Edge
• Negative Edge
• Output Energize (OTE)
• Output Latch (OTL)
• Output Unlatch (OTU)

2. Timer Logic Instruction

• Timer On Delay (TON)
• Timer Off Delay (TOF)
• Retentive Timer (RTO)

3. Counter Logic Instruction

• Count Up (CTU)
• Count Down (CTD)
• Count UP/Down (CTUD)

4. Comparison Logic Instruction

• Equal (EQU)
• Not Equal (NEQ)
• Greater Than (GRT)
• Greater Than or Equal (GEQ)
• Less Than (LES)
• Less Than or Equal (LEQ)
• Limit (LIM)

5. Arithmatic Logic Instruction

• Addition (ADD)
• Subtraction (SUB)
• Multiplication (MUL)
• Division (DIV)

6. Move Logic Instruction

• Move (MOV)
• Block Move (BKMV)
• Copy (COP)

Note :

✅ Various Types of Instruction Available In PLC.

✅ Other Instruction Use By Programmer as per Requirement.

Exclusive-NOR Gate Logic in PLC

PLC EXCLUSIVE-NOR Gate 

• We representing a Exclusive-NOR Logic Gate with two Inputs A and B.

  

  Exclusive-NOR Gate

Exclusive-NOR Gate Truth Table :

Inputs		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	1

PLC Exclusive-NOR Logic :

• When Input A and Input B both are on then upper branch provide result output 1.
• When input A and Input B both are not activated then lower branch provide output 1.
• When Input A activated then output 0.
• When Input B activated then output 0.

PLC Exclusive-NOR Gate Logic

Exclusive-OR Gate Logic in PLC

PLC EXCLUSIVE-OR Gate 

• We representing a Exclusive-OR Logic Gate with two Inputs A and B.

  

  Exclusive-OR Gate

• Exclusive-OR Gate that gives output when either of the input is 1 but when both are 1.

Exclusive-OR Gate Truth Table :

Inputs		Output
A	B
0	0	0
0	1	1
1	0	1
1	1	0

PLC Exclusive-OR Logic :

• When Input A and Input B are not on then output 0.
• When input A is activated then upper branch provide result output 1.
• When input B is activated then lower branch provide result output 1.
• When both input A and Input B are activated there is no output.

  

  PLC Exclusive-OR Gate Logic

NOR Gate Logic in PLC

PLC NOR Gate

• We representing a NOR Logic Gate with two Inputs A and B.

NOR Gate

• NOR Gate provide same result is to put NOT gate on each Input and Follow with AND Gate for resulting inverted inputs.

NOR Gate Truth Table :

Inputs		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	0

PLC NOR Logic :

• Ladder diagram starts with a normally close set of contact Input A and Input B with series with output.
• There is no input provide to Input A and Input B so contacts are closed an output on.
• There is Input provide to Input A and Input B so contacts open an output off.

  

  PLC NOR Gate Logic

Bit Logic Instruction Description

1. Normally Open (XIC)

• Normally Open contact work as a 0 state means energy flow cannot transfer so output off.
• When we provide Input and state change from 0 to 1 and output on.

Normally Open 

2. Normally Close (XIO)

• Normally Open contact work as a 1 state means energy flow transfer continuous output on.
• When we provide Input and state change from 1 to 0 and output off.

Normally Close

3. Positive Edge

• Positive Edge use for detect signal change state of 0 to 1.
• When it detect a change in the input signal from 0 to 1 energy flow transfer only of some time that signal change its state from 0 to 1.
• After energy flow can not transfer means when positive edge detect output on and off instantly.

Positive Edge

4. Negative Edge

• Negative Edge use for detect signal change state of 1 to 0.
• When it detect a change in the input signal from 1 to 0 energy flow transfer only of some time that signal change its state from 1 to 0.
• After energy flow can not transfer means when negative edge detect output on and off instantly.  

Negative Edge

5. Output Energize (OTE)

• Output Energize Instruction is an output coil. 
• Output Energize Coil state is depend on input state behavior.
• IF Input activate at that time output Coil energize on and Input not active at that time output coil energize off.

Output Energize

6. Output Latch (OTL)

• Output Latch instruction provide inbuilt latching function.
• When we provide power at Input side and Output Coil On and when we release power from input side and output coil remain on. 

Output Latch

7. Output Unlatch (OTU)

• Output Unlatch instruction provide inbuilt unlatching function.
• When we provide power at Input side and output coil off.
• This instruction use for deactivate output coil.

  

  Output Unlatch