BobW2961 (Customer) asked a question.
I have a very long rodless air cylinder. It is a pain to rebuild and seal kits are expensive. I am retrofitting the rodless cylinder to a linear motion actuator driven by a SureServo2 motor and gearbox. I hope to be able to use the 24vdc signals that were going to the cylinder's solenoid valve to trigger the servo to move. I would connect the extend and retract signals to relays and use the relays to trigger inputs on the sureservo2 drive. My question is will I be able to set the servo up in PR mode and get the same behavior that I have with the solenoid and rodless cylinder? The solenoid valve for the rodless cylinder is a 3 position double solenoid valve. So if the extend signal is given to the solenoid valve, the cylinder will move in one direction. If the extend signal is taken away, the rodless cylinder will stop where it is at. If the retract signal is given to the valve, then the rodless cylinder will move in the other direction until the signal is removed or until it moves to the end of its stroke.
With the sureservo PR mode, I hope to be able to have two positions programed. One input tells the servo to move to a position at one end of the linear actuator and another input tells the servo to move to the position at the other end of the linear actuator. If input 1 is on and the servo is moving one direction and the input is removed before the servo gets to the setpoint, will the servo stop just as the rodless cylinder would do? If that input was again given, would to continue to move towards the programmed position? Obliviously, if it reaches the programmed position then it would stop, even if the input was still on. I would have an overtravel sensor at each end of my linear actuator and I would have a home sensor. I hope is that as soon as power is supplied and the servo completes a home sequence, the servo would respond to the extend and retract signals just as the rodless cylinder did with the solenoid valve.
My second thought is would it be as simple as to have the extend signal "jog" the servo in one direction and the retract signal "jog" the servo in the other direction? This way the servo should stop moving when either signal is taken away. Would I even have to home the servo if I am only using the jog function and not actually moving to a position?
This sounds like a Velocity Reference is what you want..
In PR, the Input will cause the Drive to go to that Position and Stop.. Even if the Switch is kept closed..
What you are talking about in your 'Jog' is a Velocity Control..
Input One will Drive the Servo a Direction, until the Sig is Removed, or the EOT switch is Made..
Input Two will drive the Servo the Other Direction, to the EOT Switch.
If you know ahead of time all of the Stopping Points of the Air Cylinder, you can label them and Give it a Position Number, then Call that Position from Software or Wired Input ( Multiplexing Inputs )..
But to me it sounds like you are keeping the Same Controls, as with the AIr Cylinder.. Then if you have 'Drive Left' and 'Drive Right' Inputs.. The Move will happen at some 'Velocity', and then Decelerate when the Sig is Removed.. Or the End Of Travel Switch is Triggered..
Same Control Box, just No Air Cylinder.. Servo Drive Instead..
Cap
The speed control method (what you called velocity control) seems to be working great. I have one input that runs the motor one direction, and another input that runs the motor the other direction. I also have a speed of 0 if neither input is on and a speed of 0 if both inputs are on, which shouldn't ever happen. I am also able to set a torque limit so the pusher works just like the rodless cylinder did when adjusting the pressure to the cylinder. Thanks for the help.
Thank you for the project update.
I love it when a Plan comes Together :)
Cap
The logic for the rodless cylinder keeps the output energized at each end of the stroke.
I set a torque limit on the servo and there are gas shocks at each end that act as physical stops. The servo will contact the stops at each end and continue to try to move but will be at its torque limit. This does not generate a fault but not sure if this is an acceptable practice with the servo. It is possible that the servo could be in the condition for several minutes. Will this be a problem?