Unidirectional Mode

Unidirectional Mode, also known as Absolute Mode, is specifically designed for systems that require a unipolar control signal. Some common cases are:

Two Hydraulic Valves
Some hydraulic systems have two valves, one for direction control, the other for flow control. Unidirectional mode is for controlling the flow valve. The directional valve must be controlled by other means, but Unidirectional Mode does provide for easy switching of the control direction based on the directional valve setting.
Unidirectional Belt
A belt that must always move in the same direction.

Unidirectional Mode will prevent the Control Output from going negative even if the Actual overshoots the Target. When this occurs, the Control Output will be truncated at the Output Bias, and the Integral Term will not wind up.

Unidirectional Mode applies to closed-loop position, velocity, pressure, and force control. It does not affect the Open Loop Rate (10) and Direct Output (9) commands, but it does affect the Quick Move Absolute (15), Quick Move Relative (16), Open Loop Absolute (11), and Open Loop Relative (12) commands. The open loop portion of these moves is adjusted in the same way as a closed loop move.

For more details, see the Unidirectional Mode axis parameter.