Output Frequency
The output frequency sets the rate at which the
position pulses are sent to the servos. Each channel can be set
individually, they do not need to be the same. The normal output frequency is
50Hz for most systems. Most all analog servos and Electronic Speed Controls
(ESC) will not work faster than 50Hz and it is recommended that the output
frequency be set no faster than that for most applications. There is no
advantage at all to running faster than 50Hz if both of the SM2 input
cables are plugged into receiver outputs. This is because the receiver
outputs are posted at about 50Hz and therefore the SM2 output pulses
will not change any faster than that. The only place where faster rates are desirable is
when gyros are used with digital servos to stabilize a vehicle. Many upper-end
gyros will produce faster position pulses so that the servo can react faster to
external influences such as wind. If the gyro is set to provide pulses at 150Hz
then the servo will begin to respond to external influences 3-times faster than
it would at 50Hz. The fact that the receiver only provides position pulses
at 50Hz does not prevent the system from responding quicker to gyro inputs. This
faster response time can make a big difference in control system damping and can
often avoid oscillation and other adverse effects associated with slower sensory
input. Only use output frequencies faster than 50Hz when a
sensor such as a gyro is plugged into one of the SM2 inputs, and the sensor
is capable of updating and posting position pulses faster than 50Hz. Set the
output frequency to at least match your sensor output, preferably a
little faster. Make sure your servo can handle the higher rate by checking
the servo specifications. Test the servo
operation by setting the output frequency on the SM2 Control Panel
Application and using the "Program Device" function to set the output
frequency on the SM2. The output frequency cannot be simulated so you must
program the device to test different settings. Use the "Output Frequency" slider bars to set the
rate at which the position pulses will be sent from the SM2. A warning note will appear on the SM2
Control Panel Application if the output frequency is set much higher than 50Hz
to make sure the operator understands that some servos may not work.
2-Channel Standard Mixer SM2
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