The mass flow of air leaving the pneumatic cylinder (to atmosphere) is controlled with the combination of an electronic mass flow control valve, a mass flow monitor, a traditional four-way/five-port solenoid valve and sometimes an additional electronic pressure regulator. The solenoid valve is used to change the cylinder direction between extend and retract. But regardless of whether the pneumatic cylinder is extending or retracting, the speed of extension or retraction is always being controlled by the electronic flow control package by metering out the exhaust from the pneumatic cylinder.

Because the electronic set point command to the pneumatic cylinder can be varied, the velocity can be varied on the fly. A soft start and a soft stop can be programmed into the PLC, and this can really decrease wear and tear on the pneumatic cylinder.