Projecta IM2000 Instruções de Operação descarregar pdf (Página 17)

PWM circuit uses alternating recirculating/non-recirculating modes to

accurately regulate the current in the windings of a two phase stepping motor.

Microstep Select (MSEL) Inputs

Another unique feature of the IM2000 is the ability to change resolutions at

any time. A resolution change can occur whether the motor is being clocked or

is at rest. The change will not take place until the rising edge of the next step

clock input. At this time, the new resolution is latched and implemented before

the step clock pulse takes effect.

If a resolution is chosen such that the sine/cosine output of the IM2000 would

not land on an electrical fullstep of the motor, then the IM2000 will automati-

cally align itself to the full step position on the step clock pulse that would

have caused the motor to rotate past the full step. The step clock pulses, from

that point forward, will be equal to the selected resolution. This feature allows

the user to switch resolutions at any time without having to keep track of sine/

cosine location. Because of this, the On-Full-Step output of the IM483 can

easily be used to monitor position.

Configuration settings for the Microstep Resolution are located in Section 7 of

this document,

Interfacing and Controlling the IM483.

Stepping

The IM2000 contains a built-in sine/cosine generator used for the generation of

Phase A and Phase B position reference. This digitally encoded 9 bit sine and 9

bit cosine signal is directly fed into a digital to analog converter.

The step clock (SCLK) and direction (DIR) inputs are buffered using Schmidt

triggered buffers for increased noise immunity and are used to increment or

decrement the sine/cosine position generator. The position generator is

updated on the rising edge of the step clock input. It will increment or

decrement by the amount specified by the microstep resolution select (MSEL)

inputs.

The direction (DIR) input determines the direction of the position generator

and hence the direction of the motor. The DIR input is synchronized to the

SCLK input. On the rising edge of the SCLK input the state of the DIR input

is latched in. The position generator will then look to see if there has been a

change in direction and implement that change before executing the next step.

By utilizing this method to implement the direction change, the noise immunity

is greatly increased and no physical change in the motor occurs if the direction

line is toggled prior to the step clock input.

The enable/disable input does not affect the step clock input. The sine/cosine

generator will continue to update if a signal is applied to the step clock input.

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 76 77

Sem comentários

Projecta IM2000 Instruções de Operação Página 17