Toggle switch & Push button switch

Dear all

I want any one to get me out of that hole, any help would be appreciated......

I want to know why all Plc application deal with pushbutton switches, is there any difference between them except the latch i used with pushbutton to keep the effect of being on after touching it.

is there any priority to use pushbutton instead of Toggle switch.

any help would be great.

There is no obligation to use push buttons with PLC.Push button is an input device .From the PLC point of view there is no difference between it and toggle switch,limit switch/proximity switch,photo cell or even a relay contact they are all input devices.
Best Luck

A matter of degrees

The reason you see push buttons being used so often is because they are really in use that often. Think of the many times on machine or process controls that an operator pushes a button to make something happen. As heshem put it

toggle switch,limit switch/proximity switch,photo cell or even a relay contact they are all input devices

Click to expand...

Most people use what is familiar to them and it often turns out to be a pushbutton.

Instances when a pushbutton are used are:

• When a process is started by an operator action and ened by pushing another pushbutton, a time delay, an actuator making a limit switch, etc. This is where you see the "latch" you spoke of.
• When it is important that the process stop when the pushbutton is released. This will be programmed without a latch.

You see much of those examples because they common things that are done, not because pushbuttons are supposed to be used only.

We use two and three position selector switches all the time as well. These are used if the process should remain on after power is reapplied, etc.

The use of PBs and SSs is the same for PLC based control as it would be for hardwired relay based control.

As I tell people I train in PLCs, just because I do something one way, that doesn't make it the right way. What makes it right is, that it works, it is safe and that the next guy who comes along after you can trouble-shoot it and get things running again when something does go wrong.

Edit: That is not to say that there are not some things that are a better practice than others.

m_abd_el_khalik said:

...is there any priority to use pushbutton instead of Toggle switch...

Click to expand...

SAFETY

A push button need to be activated.
A toggle switch is where it was left last time.

Power down and power up means re-activating you PB but the toggle switch will remains in place.

So any "Recipe" function (Ex: auto/man) are best with Selector switches BUT actions need PB (Ex: Start/Stop)