Two-hand Safety with Anti-tie-down Feature – The Ladder Program

In two-hand safety operations in dangerous industrial operations, such as a pneumatic press, the hands of an operator must be engaged for safety reasons. This condition is usually achieved by arranging two pushbuttons (Say, PB1 and PB2) arranged at a distance.

That means, the operator cannot press the pushbuttons with one hand. At times, there is a tendency on the part of operators to latch one of the pushbuttons by other means and operate the machine with one hand and adjust work-piece or tools with the hand.

The pushbuttons must be pressed within a very short time, say one second to get the anti-tie down feature. A ladder program to implement this control requirement taking a lamp as the representative output device.

Ladder Program

Programmable Logic Controllers and Programming Concepts

With Electrical, Pneumatic, and Hydraulic Applications

Joji Parambath

Authored by

Joji Parambath


Fluid Power Educational Series

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