Pulse output function for programmable logic controller with linear frequency change

A machine-readable medium containing instructions for activities comprising:

• in a programmable logic controller, automatically changing a first user-specified pulse frequency to a second pulse frequency;
• and
• automatically outputting a plurality of pulses from the programmable logic controller at frequencies varying between the first user-specified pulse frequency and the second pulse frequency according to a user-specified linear-time-rate variation.

A system for producing pulsed outputs comprising:

• a pulse generator adapted to produce linear changes in frequency with respect to time by adding or subtracting a specified frequency increment to a specified frequency at regular specified intervals to create a frequency specification,
• a divider mechanism adapted to convert the frequency specification to a pulse width specification,
• a pulse width generator adapted to produce a desired pulse output by counting clocks of a fixed reference frequency according to the pulse width specification.