Counter and its Function/Automation/Industrial Automation/PLC counter

What is counter

A counter may be a digital circuit or device that counts the amount of products and returns predefined values supported clock pulse applications. The output of the counter are often wont to count the amount of pulses. The counter circuit is typically composed of several flip-flops connected within the cascade method. Counter automation and digitally based components are very widely used components.

     Micro controller applications require external events or precise internal time delay generation and calculation of pulse frequency as required . These phenomena are often utilized in digital systems and automation. Both of those events are often performed by software techniques, but software loops for counting won't give accurate results, as little more important work isn't done. These problems are often corrected by timers and counters in micro controllers that are used as interrupts.

Classification of counters

In digital circuits, counters are often implemented using register-type circuits like flip-flops,

The counters are classified as given below.

 Asynchronous or Ripple Counter - Sequence state flip-flops are used as clocks to define the Ripple Counter because the Replay Counter State. additionally , asynchronous counters are less useful than synchronous counters in complex, high-frequency systems.

 Synchronous Counter - A synchronous counter has an indoor clock, while asynchronous counters don't . As a result, all flip-flops during a synchronous counter run simultaneously by one , normal clock pulse. (All state bits are converted to one clock control)

Plc counter

            The PLC counter may be a function block that counts until or below a given threshold. Now-a-days PSC may be a tool widely utilized in industrial automation. PLC counters also are utilized in SCADA systems by calculating allocated act . once you are allocating a task, counters widely utilized in PLC programming to count what percentage times a process has been completed. Or what percentage products are produced.

How to address a counter in PLC

Counters use variables of some data types to store numbers during a PLC. All counters are required to store a minimum of two numbers, these two numbers are saved during a fixed data type, which also has their limitations. Many PLCs save these two numbers as WORD or Integer data types.

Below shown addressing for the PLC 

 UP Counter: this is often wont to indicate when a count has reached the utmost 'up count' value.

Input

Signal	Data type	Description
EN	BOOL	Enables block operation
R	BOOL	Reset CV
PV	UINT, UDINT	Preset value of the up counter

Outputs

Signal	Data type	Description
ENO	BOOL	Indicates completion of operation
CV	UINT, UDINT	Current value of the up counter

Block Representation in Ladder.

Operation in LD:

Variable Table:

UP COUNTER RPS:

Up counter rps is Used in device for a  signal when a count has reached a maximum ‘Up count’ value with input pulse Frequency measurement. The Selection of Averaging Time & Averaging Pulses for frequency measurement is provided.

Inputs

Signal	Data type	Description
CU	BOOL	Pulse input - Count Up
R	BOOL	Reset CV
PV	UDINT	Preset value of the Up counter
AT	UINT	Averaging time for RPS update in 0.1s resolution (0.1 to 6553.5s)
AP	UINT	Average number of Pulses for RPS update (1 to 65535)

Outputs

Signal	Data type	Description
ENO	BOOL	Set when CV >= PV
CV	UDINT	Current value of the Up counter
RPS	UINT	Calculated RPS value in 0.01Hz resolution (0.01Hz to200Hz)*

Accuracy:- +/– 1ms

Update:– Every AT or AP whichever occurs first

Note:-Averages RPS of IP pulses on CU pin will be calculated depending upon value of AT & AP as mentioned in below table.

AT	AP	RPS Output Calculated & Updated
> 0	= 0	every 'Average Time'
= 0	> 0	when No of input pulses >= 'Average Pulses'
> 0	> 0	condition that satisfies first (as per above 2 steps)
= 0	= 0	every input pulse

Check the Example Given below

Input			Output	Update time (sec)
Input Pulse @ CU	AT (sec)	AP	RPS output (Hz)
10 Hz	0	50	10.00	5
20 Hz	0	50	20	2.5
25 Hz	1.5	0	25.00	1.5
30 Hz	2.0	80	30.00	2
100Hz	2.0	80	100	0.8
50 Hz	0	0	50.00	Every pulse (20ms)

LD Representation :

Ladder:

Variable Table :

·          Up/down counter – counts both up and down, under command of a control input

Inputs:

Signal	Data type	Description
CU	BOOL	Count Up
CD	BOOL	Count Down
R	BOOL	Reset CV
LD	BOOL	Used to set CV with PV
PV	INT, DINT	Preset value of counter

Outputs:

Signal	Data type	Description
QU	BOOL	set when CV >= PV
QD	BOOL	set when CV <= 0
CV	INT, DINT	Current value of counter

Representation in LD:

Operation in LD:

Variable View:

Down  counter –Down counter is Used to signal when a count has reached zero value

Inputs

Signal	Data type	Description
EN	BOOL	Enables block operation
R	BOOL	Reset CV
PV	UINT, UDINT	Preset value of the down counter

Outputs

Signal	Data type	Description
ENO	BOOL	Indicates completion of operation
CV	UINT, UDINT	Current value of the down counter

Representation in LD:

Operation in LD:

Variable Table :

All counters are supported different applications in industry. Plc counter avoid the external expenses of shopping for a counter. In plc counter is inbuilt so got to connect External counter to  automatic counts.

Note:

1. once you are communicating the plc online or offline you want to give the right address for a input & output. Every input & Output define in Boolean expression only

2. All the function block define consistent with there application so it's going to be integer,Double Integer, Word or Double Words. All the counters Preset and cv value expressed in Int or Double int.

1. A counter may be a PLC instruction that either Increment(counts up) or decrements (counts down) an integer number value when actuate by the passage a touch from 0 to 1 (“false” to “true”). Counter instructions are available three basic types: up counters, down counters, and up/down counters.

 Uses Of Counters

1. Counters are often utilized in industries for time delays and production monitoring.

2. Cement manufacturing.

3. Paper industry etc…