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The Control board serial port signals connect to the Power Supply/RF board through the
96-pin connector. The signals are then connected to the 9-pin serial port connector on
the Power Supply/RF board.
Dosage Error Algorithm
Dosage Error Algorithm for Closed-Loop Modes
The dosage error algorithm for the closed-loop modes (bipolar and cut) is based on a
comparison between the actual power as calculated by the main microcontroller (U5)
using the backup sensors and the maximum allowed power.
While the feedback microcontroller is operating the generator output, the main
microcontroller calculates and checks the values to make sure the feedback
microcontroller is operating the generator properly.
In a closed loop mode, there is a 500 ms delay before the dosage error algorithm
monitors the RMS output of the generator. After the delay, the algorithm first checks to
see that the voltage, current, and power calculated by the backup sensors are less than
125% of the value calculated by the primary sensors.
On passing this test, the feedback mode of the generator is taken into account.
• In current control mode, the current calculated by the backup sensors is not allowed
to deviate from the current calculated by the primary sensors by more than 50% of
the value calculated by the primary sensors.
• In voltage control mode, the voltage calculated by the backup sensors is not allowed
to deviate from the voltage calculated by the primary sensors by more than 50% of
the value calculated by the primary sensors.
During closed loop activation, the main microcontroller continually checks for broken
backup sensors. The current and voltage sensor analog values are compared to the
previous readings to ensure that the sensor values are not constant or falling while ECON
is rising.
When the generator drops into spark control, the software makes allowances for the
shift in frequency. The voltage sensor returns a value that is approximately 20–25% high,
and the rms value calculated for the voltage sensor is reduced by 25%. The current
sensor returns a value that is approximately 10–15% low, and the rms value calculated
for the current sensor is increased by 12.5%.
The dosage error algorithm for the open loop modes (coag) is based on the ECON
calculated for the mode. The main microcontroller calculates an ECON that represents
125% of the front panel power setting and verifies that SYS_ECON and HV_SEN do not
exceed this value while the generator is activated.
These tests detect stuck or aberrant sensors and improperly delivered power in all modes.
The dosage error firmware executes in less than one second.
Force FX Electrosurgical Generator C Service Manual
Control Board
4-11
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