Copley Controls: Stepnet Panel (STP Series)
20-75 VDC & 115-230 VAC Digital Drives for Stepper Motors
Stepnet is a stepping motor drive that combines CANopen networking with 100% digital control of stepping motors. When used with Copley's Accelnet™ and Xenus™ digital servo drives it makes possible brushless, brush, and stepping motor control over the same distributed network.
In Servo Mode, steppers fitted with encoders can be operated as DC brushless servo motors in current, velocity or position modes. This enables the motor to operate at higher RPM’s without stalling which might occur in open-loop operation as a stepper.
Stepnet can operate as a stand-alone drive accepting incremental position commands from step-motor controllers in Step/Direction or CU/CD format, as well as A/B quadrature commands from a master-encoder. Pulse to motor position ratio is programmable for electronic gearing.
Setup is fast and simple using CME 2™ software operating under Windows® and communicating with Stepnet via an RS-232 link. CAN address selection is programmable in flash memory, by rotary switch on the unit or via programmable digital inputs. Stepnet operates as a Motion Control Device under the DSP-402 protocol of the CANopen DS-301 V4.01 (EN 50325-4) application layer. DSP-402 modes supported include: Profile Position, Profile Velocity, Interpolated Position Mode (PVT), and Homing Modes. When operating in Servo Mode, Profile Torque mode is available. The CAN bus interface is optically isolated from the drive circuits. Profile Position mode does a complete motion index on command with acceleration & deceleration, top speed, and distance programmable.
In PVT (Position-Velocity-Time) mode, the controller sends out a sequence of points each of which is an increment of a larger, more complex move than that of a single index or profile. The drive then uses cubic polynomial interpolation to “connect the dots” such that the motor reaches each point (Position) at the specified velocity (Velocity) at the prescribed time (Time). Homing mode is configurable to work with a combination of limit and home switches such that the drive moves the motor into a position that has an absolute reference to some part of the machine. Profile Velocity mode controls velocity, acceleration, and deceleration with no target position defined.
There are twelve logic inputs. Input [IN1] is dedicated for drive Enable. Eleven are programmable as limit or home switches, stepper pulse inputs, A/B encoder, reset, CAN address, or motor over-temperature sensor. There are four programmable logic outputs for reporting a drive fault, operating a motor-mounted brake, or other status indications. When operating as a node on a CANopen network, the inputs and outputs can be read or controlled as independent I/O points that are not linked to drive operation. An Aux HV input is provided for “keep alive” power that preserves the drive data (e.g. current position) and CANopen operation if +HV has been removed as in an emergency-stop situation. This enables the control system to monitor drive status and to enable an orderly recovery without a full system reset, and homing of all axes. Operation from transformer-isolated DC power supplies saves cost in multi-axis systems.
Indexer, Point-to-Point, PVT
Camming, Gearing
Position, Velocity, Torque [Servo Mode]
Position (Microstepping)
