Switching

SWITCHING IN PLC

We basically have three types of switches:

(i)                 Momentary Switch

(ii)               Latch Switch

(iii)             Float Switch

Among these three types of switches two of them are

DIGITAL SWITCHES

ANALOG SWITCHES

(I)               Momentary Switch:- These Switches are of two types:

(1)   Normally Open (Examine if Closed)

(2)   Normally Closed (Examine if Open)

(II)       Latch Switches:-

                 These are reverse two way switches which we use at our home in bed room in stairs.

(II)           Float Switches:-

These are reverse along switches whose value varies.

(1) Normally Open:-

          An input can be a connected switch closure or sensor, a contact from a connected output, or a contact from an internal output. When interpreted, the referenced input or output is examined for an ON condition. If its status is 1, the contact will close and allow current to flow through the contact. If the status of the referenced input/output is 0, the contact will remain open, prohibiting current from flowing through the contact.

(2) Normally Closed:-

          An input can be a connected switch closure or sensor, a contact from a connected output, or a contact from an internal output. When interpreted, the referenced input/output is examined for an OFF condition. If its status is 0, the contact will remain closed, thus allowing current to flow through the contact. If the status of the referenced input/output is 1, the contact will open, prohibiting current from flowing through the contact.