stepper controller and computer controlled switch

[windell747]

I'm wanting to purchase a stepper motor controller that will idenpendantly control either one or two (independently) 12 volt unipolar stepper motor with a 3A phase current.

I would like to feed ascii characters to this motor controller via a Linux PC RS232 com port commanding it to rotate the steppers. I would also like the controller to monitor the the feeback of an optical encoder and stop the steppers when the encoder has reached a certain position. Although, I would prefer the controller to monitor the encoder, I could also have the PC monitor the encoders position and have it command the controller to stop the motors. After the controller has finished rotating the motors, I would like the controller to pass back a command telling the PC that it is done rotating the antenna.

I would also like the PC to be able to cut all power to the controller and both steppers with some type of computer controlled relay via the PC's RS232 port.

I have already done a lot of searching online using google and I have found many different choices. I am wondering if
you have any suggestions or recommendations.

In addition, do you have any suggestions as to a computer controlled switch or relay to power up and down the controller and stepper system?

mahalo