Two Hand Control is a method
of Machine Safety where both Operator's hands must be in a safe place to operate
a machine. In many cases Safety Category 4 per ISO 13849-1 (EN 954-1) is
required and functional Type IIIC two-hand control in accordance with European
Standard EN 574. This may be achieved using Self-Checking Touch Buttons IN
COMBINATION with the corresponding Control Module.
The Self-Checking STB Buttons
feature redundant microprocessor and an optical path which is broken by
inserting the finger. Covers avoid attempts to use another method of actuating
and both buttons must be actuated simultaneously (within half a second) to avoid
To ensure reliability,
control modules have a diverse-redundant microcontroller circuit and multiple
redundant, force-guided (mechanically linked) output contacts.
Anti-tiedown logic requires that both touch buttons are activated within
one-half second of each other.
Optional mute inputs allow release of actuating buttons during the non-hazardous
portion of the machine cycle.