Velocity (Oscillator) Mode - Flex IO Drives

In velocity mode, the motor's speed is controlled by analog and digital inputs. If you have used an Applied Motion "O" or "PDO" drive in "oscillator mode", you're in the right place. The STM drive+motor can do everything the "O" and "PDO" drives can do and more.

The Velocity Dialog for these drives allows you to set up the drive for velocity mode and configure all available I/O.

• Check the box marked "Use I/O#1 as Run/Stop" if you want to command the drive to run using a switch or a signal form another electronic device. If you do not check this box, the motor will run at all times (unless you have also chosen "Speed proportional to analog input" and the analog input voltage is at 0.)
• I/O#2 always controls the motor direction. The analog input can also change the motor direction if you have an offset (see Advanced Settings, below)

Options for I/O#3 include:

• Change motor speed - when closed, the motor will run at a different speed, which you must enter to the right of the "Change motor speed to"
• Enable motor when closed - the motor will be disabled when this input is open.
• Enable motor when open - opposite of above.
• Reset alarm when closing - I/O#3 can be used to clear an alarm or fault by closing it
• Reset alarm when opening - I/O#3 can be used to clear an alarm or fault by opening it.  Also re-enables the motor.
• General Purpose Input - not automatic function for EN, but its state can be read using the SCL IS command. Can also be used by SCL FS and FY commands.

Options for the I/O#4 are:

• Closed on fault - output will close if a fault occurs
• Open on fault - output is normally closed and opens if a fault occurs
• Closed to release brake - output controls a fail safe brake relay
• Open to release brake - same as above but output opens to release the brake
• Closed when moving - output closes whenever motor is moving
• Open when moving - output opens whenever motor is moving
• Tach out - output produces pulses relative to the motor position
• General Purpose Output - output has no automatic function but can be controlled by the SCL SO, FO, IH and IL commands.

If you simply want the drive to run at a constant speed anytime it is on, uncheck all the boxes, enter a speed in the text box and an accel rate in the accel box. As soon as you download your configuration, the motor will run

In most applications, you'll need to stop the motor. The simplest way to do this is to check "Use I/O#1 as the run/stop input." When the I/O#1 input is closed, the motor will accelerate to the speed you've chosen at the acceleration rate you entered in the "Accel" box. When X1 opens, the motor decelerates to a stop using the value in the "Decel" box.

If you need two speeds, check "Use I/O#3 as change speed...". This option allows to you to enter a second speed. The motor will accel or decel to the second speed anytime I/O#3 is closed. When I/O#3 opens, the motor speed changes to the first speed, again according to the accel and decel rates you've entered.

Need more speeds? These drives include an analog input that can be used to set the speed when I/O#3 is open or not used. Just select a voltage range to match your signal (0 to 5 V, 0 to 10V, +/-5V or +/-10V), then enter a speed that corresponds to the speed you want at your maximum input voltage. If you apply less than the maximum, the motor speed will be proportional to the applied voltage.

If you plan to use a potentiometer to adjust the speed, it's best to select "0 - 5V" as the range, then connect the drive's 5V power output to the potentiometer's "cw" terminal.

If you want to use a joystick to operate the drive in both directions, you'll need to enter an offset that is half the voltage range. If you're using the drive's 5V output to power your analog joystick, set the offset for 2.5V. Click the "Advanced Settings" button to change the offset.

Direction

I/O#2 is used to select the direction of rotation. If the motor is moving when you change the state of the direction input, the motor will decelerate to stop then accelerate to the same speed in the opposite direction.

Motion Output

I/O#4 can be used to tell another piece of electronics when the motor is moving in velocity mode. If you want the signal to indicate when the motor is in motion you have two choices: the output can be closed when the motor is moving and open when it is stopped, or it can be open when moving and closed when stopped. If you want a tachometer output (a signal proportional to the motor speed), I/O#4 can emit pulses as the motor turns, 100 square wave pulses per revolution (assuming you have a 1.8° motor, otherwise you get 2 times the motor electrical frequency).

Additional settings of 200, 400, 800 and 1600 pulses/rev are available for drives with DSP firmware version 1.02 or later. However, the tach output’s maximum frequency is fixed, so the integrity of the tach output signal at higher resolutions is dependent on motor speed.  Suggested speeds ranges for the different tach output resolutions are shown in the table below.

Note: Signal integrity is best with an 80 mA load (use 300 ohms at 24V, 150 ohms at 12V or 62 ohms at 5V.)

Advanced Analog Settings

• Deadband: If you need your analog signal to be able to stop the motor, but the signal doesn't quite go to zero volts (potentiometers can usually go to zero volts, but electronic circuits usually can't) then you'll need a "deadband". This is the range of voltages in which the motor does not run. It is specially useful to get the motor to stop when you let go of the joystick.
• Offset: This setting is most often used for a single ended (unipolar) joystick.  With such a device, the output signal is typically 0V when the joystick is pressed to one extreme, 5 volts at the other extreme and 2.5 volts when at rest in the center.  By entering an offset of 2.5 volts, the motor speed with be increasingly clockwise as the joystick is "pushed forward" and increasingly counterclockwise when the "pulled back" from it's neutral position.
• Filter Frequency: If your analog signal is noisy you may notice the motor speed changing when it should be constant. It is not unusual for industrial systems to pick up some electrical noise on an analog wire and the ST's high resolution 12 bit analog input may respond to the noise. In that case you should lower the analog filter frequency (in the "Advanced Settings" dialog) until the problem goes away. If you set the frequency too low, the motor may change speeds more slowly than you specified in the accel and decel boxes because of excessive filtering, so try not to overdo it.