Basic step and direction drives for powering step motors abound in the marketplace, and it takes dedication to set our drives apart from the pack. We do this by developing innovative control solutions that make step motors perform better (faster, quieter, smoother, more accurately, and with more torque), without breaking the budget. We also differentiate our product line by offering drives that are smarter than basic drives. This article touches on a smarter class of step motor drives, including the popular ST5-S stepper drive, that can be controlled by higher level streaming commands.
Basic Step Motor Drives
Step and direction drives are the perfect choice for many applications because readily available machine controllers – like PLCs, motion controllers, indexers, and PCs – can generate the digital step (pulse) and direction signals necessary to control the motion of the motor. However, care must be taken to select a controller with a digital output specification of 2 MHz or higher if using microstepping, and depending on the controller selected, generating the code to create the motion profiles can be time consuming.
Beyond Basic Drives
For many other applications, a drive that can accept higher level commands via a permanent serial connection – such as RS-232, RS-485 or Ethernet – provides another option for system designers who prefer not to mess with coding up the motion profiles and would prefer instead to rely on the smart step motor drive to generate the profiles internally. In this scenario the designer provides high level commands to the drive that describe the parameters of the motion profile, i.e. acceleration, deceleration, constant velocity, and distance or position, and the drive takes care of generating the necessary pulses and controlling the motion of the step motor. This approach, commonly referred to as “streaming commands”, frees up programming time, reduces discrete I/O count, and potentially alleviates a lot of headaches.
Sample Higher Level Command Sequence
Below is a typical sequence of higher level commands for an Applied Motion drive. This sequence includes one command for each parameter of the motion profile: acceleration rate, deceleration rate, velocity, and distance traveled. At the end of the sequence a single command initiates the defined motion from the motor.
|AC100||Set acceleration rate to 100 rev/sec/sec|
|DE100||Set deceleration rate to 100 rev/sec/sec|
|VE5.5||Set motor velocity to 5.5 rev/sec|
|DI10000||Set move distance to 10,000 steps|
|FL||Initiate an incremental positioning movement (AKA Feed to Length)|
The ST5-S Stepper Drive
The ST5-S stepper drive is a prime example of a smart step motor drive that provides this higher level capability via streaming commands. The ST5-S provides up to 5.0 amps/phase to drive 2-phase step motors from the small size NEMA 11 up to the large size NEMA 34. It has an attractive list price and is ready to ship from our warehouse in California.
For applications requiring more torque with bigger motors check out the ST10-S stepper drive.
For more drives that accept streaming commands click here.
For the full list of higher level commands available in our drives click here.