Introduction to specific functions
The specific functions of step by step axes control apply to the whole control system made up of:
-
the command
-
the translator
-
the step by step motor.
The important ideas are as follows:
Diagram of the step by step axes control system
This diagram describes a typical step by step axes control system.
|
Block
|
Description
|
|
Command
|
The command function is carried out by a channel of a TSX CFY 11 or 21 module. The principal function of this channel is to provide a series of pulses of constantly controlled frequency, in order to carry out the required functions.
|
|
Translator
|
The translator’s essential function is to transform each received pulse into a step (elementary rotation) of the motor, by circulating suitable currents in its windings.
|
|
Step by step motor
|
Step by step motors are built according to different technologies. For example permanent magnet motors, variable reluctance motors and hybrid motors which combine the two techniques. Furthermore, different winding solutions exist on the market: two, four or five phase motors.
Each type of motor is thus associated with a specific type of translator optimized for its technology.
|
The control of different step by step systems must generally obey a common restraint, due to the response of the inertial system (motor and axis) to a pulsed command. The common constraint is the start stop frequency.
The start stop frequency is the frequency at which the motor can stop or start without ramp and without losing step. Its maximum threshold depends upon the external inertia related to the motor axis. Its average value is 400 Hz in a 1/2 step (1 turn/sec) and can be critical beyond 600/800 Hz (1.5 to 2 turns/sec) (typical values for Phytron Elektronik tranlators/200 step motors/lathes).
This constraint exists at the stopping as at the starting of all movements, whence its name: start stop frequency, SS_FREQ. The TSX CFY modules allow you to adjust this value.
NOTE: in this manual, the terms frequency and speed are used interchangeably. In the same way, the units of pulse position and pulse are the same. It is the same for the units of speed Hertz and Pulses/s and the acceleration units Hertz/s and Pulses/s 2.
Some translators have a boost input. This function consists in increasing the current in the motor windings.
The boost output from a channel of a TSX CFY module controls this input to the translator. It is thus possible to control the intensity of the motor current in synchronization with the movement. Notably automatic control mode for this output supports its activation during acceleration and deceleration phases.
When a brake is present on the axis, this static output supports its control in synchronization with the movement or at the request of the user.
This function is useful when you want to interrupt the supply to the motor in load carrying applications.
NOTE: when the channel is in the safety position, this output makes the brake active (generally the brake is active when voltage is absent).
