TIMERS & COUNTERS

TIMERS & COUNTERS

The Islamic University of Gaza

Electrical Engineering Department

Eng. Mahmoud H. Munia

2021

FUNDAMENTALS OF TIME DELAY RELAYS FUNCTIONS

Fundamentals of time delay relays functions:

Time delay relays have a time-delay function built in. Triggered in different ways. There are three main types of those timers:

• ON Delay Timers.

• OFF Delay Timers.

• Cyclic Timers.

ON-Delay Timers:

Normally open, on-delay timers start timing when the input voltage (power) isapplied. The output is energized at the end of the delay. Input voltage has to beremoved to de-energize the output and reset the time delay relay.

OFF-Delay Timers:

OFF-Delay timers are ready to accept the trigger when the input voltage is applied.An output is energized by applying the trigger, which must be removed for thetime delay to start. An output is de-energized at the end of the time delay period.If the trigger is applied during the delay, it will reset.

Cyclic Timers:

The output is on for a specific time (on-time) and off for another specific time (off-time)

Setting an output with a TMR – timer in delta plc programming

EXAMPLE(1):

TMR FUNCTION:

To use a TMR we need to know a few things:

• First of all at what rate the timer runs.• In delta plc’s the timer generally runs at 100ms.

Here below is a table of the different timers you can use in your delta plc programs.

TMR FUNCTION:

So if you want to have your timer run at 100ms intervals you need to choose a timerbetween T0 – T63. If you are looking to run a timer which has 10ms intervals you need touse T64 – T126. For 1ms intervals you only have the one timer which runs on T127.

EXAMPLE (1): Setting an output with a TMR

Our purposes to have the TMR run for 5 seconds before turning Y0 on. Let’s use the mostcommon timer which is the T0 – T63 timer which runs at 100ms. (we need 50 increments of our timer.)

Resetting timers and outputs

EXAMPLE(2):

EXAMPLE (2): Resetting timers and outputs

Repeat example 1, but with turning Y0 offafter 3 seconds and then have it off for 5seconds and turn it back on and loop throughthat procedure automatically.

FUNDAMENTALS OF COUNTER FUNCTIONS

Fundamentals of Counter functions:

Counters can be used to do various things, such as count batches, movements in aprocess or cycle, production numbers, or even keep track of which step in the process weare at. Let’s start with a basic counter example just to get you into the swing of things.

Here below is a table of the different counters you can use in your delta plc programs.

Setting an output with a CNT – counter in delta plc programming

EXAMPLE(1):

EXAMPLE (1): Setting an output with a CNT

Start a new ISPSoft project and add the following to the first network. Start with a LD X0 then hit enter againand type : CNT C0 10

This basically much like timers will produce a counter which will count up to 10 then energize the C0.

Product Packaging on counter Basis

EXAMPLE(2):

EXAMPLE (2): Product Packaging on counter Basis

Once the photoelectric sensor detects 10 products, the robotic arm will begin to packup.When the action is completed, the robotic arm and the counter will be reset.

Control Purpose:

Devices:

EXAMPLE (2): Product Packaging on counter Basis

Control Program:

EXAMPLE (2): Product Packaging on counter Basis

Program Description:

• Once the photoelectric sensor detects a product, X0 will go from OFF to ON once, and C0 will count for one time.

• When the present value in C0 reaches 10, the Normally Open contact C0 will be closed. Y0 = ON, and the robotic arm will begin to pack.

• When the packing is completed, the robotic arm action completed sensor will be enabled. X1 will go from OFF to ON and RST instruction will be executed. Y0 and C0 will be reset for the next packing task.