Devices and techniques for cutting and coagulating tissue

A method of driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising:

• receiving, by a generator, a frequency slope threshold;
• monitoring, by the generator, a frequency slope of the ultrasonic drive system;
• comparing, by the generator, the frequency slope of the ultrasonic drive system with the frequency slope threshold;
• and
• incrementing, by the generator, a timer when the frequency slope is less than the frequency slope threshold.

A generator configured to drive an end effector coupled to an ultrasonic drive system of a surgical instrument, the generator comprising:

• a processor;
• a timer circuit coupled to the processor;
• a timer latch coupled to the processor;
• a condition set latch coupled to the processor;
• and
• a memory coupled to the processor, wherein the memory includes machine executable instructions that when executed by the processor cause the processor to:
• receive a frequency slope threshold;
• monitor a frequency slope of the ultrasonic drive system;
• compare the frequency slope of the ultrasonic drive system with the frequency slope threshold;
• and
• increment the timer circuit when the frequency slope is less than the frequency slope threshold.