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

Author

Fluid Power Educational Series

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