Analog control of a Stepper Motor

[Aberdeen57]

I am looking to integrate a stepper motor into a ethernet-based system I have been developing.

The signal path is as follows:

Visual Basic Code on Comp --> Ethernet --> Digital Controller --> Analog Signal --> ? --> Stepper Motor Driver --> Stepper Motor.

The question mark is the focus here. The analog signal coming from controller is +/- 10VDC with 2mA. The stepper motor driver is an R208 driver (**broken link removed**) which requires a frequency signal of 5Volts, 50%duty cycle, pulse train and a square wave to control the steps. The stepper motor itself is a 1.12amp/phase bipolar motor.

My question is how can I use the analog signal to control the stepper motor? I need to be able to control the number of steps and direction. The step speed does not need to be variable.

I appreciate any help as I am still new to this field!

 

[fsmyth]

One simple method would be to use something similar to:
4-Phase Stepper Motor Drivers
Replace the timing resistor with an optocoupler.

 

[Ubergeek63]

Why would you take an inherently accurate digital signal controlling an inherently accurate digital device and stick inherently inaccurate, noise susceptible analog in between?

I can not think of any way of doing that short of a second processor to do all the work. If you want to assume it starts at some home location, which it likely will not do reliably, you could say your messy analog represented a count and using charge transfer to measure how many steps you have taken to close a feedback loop controlling a quadrature oscillator, but why bother?

 

[Mikebits]

Skip the analog portion. Like

Visual Basic Code on Comp --> Ethernet --> Digital Controller --> Stepper Motor Driver --> Stepper Motor.

Maybe if you were more specific about your hardware.

 

[Ubergeek63]

Skip the analog portion. Like

Visual Basic Code on Comp --> Ethernet --> Digital Controller --> Stepper Motor Driver --> Stepper Motor.

Maybe if you were more specific about your hardware.

I must admit to getting a bit pessimistic. More and more whenever I see a "project" obviously far beyond the questioner's technical competence, I think it is some "entrepreneur" with a get rich quick scheme.

 

[Aberdeen57]

The reason for the analog signal is that I do not have a digital output from the controller to work with.

The ethernet controller is a Sensoray 2601 (**broken link removed**)

The analog input/output device is a Sensoray 2608-8
(**broken link removed**)

I am using these cards because of the other portions of this system into which the stepper motors would be integrated. The device has a multiple tranducers, flowmeters, solenoids, and regulators to control other functions.

Am I correct in that you all are suggesting that using an analog out to control the motor not feasible?

 

[Aberdeen57]

The reason the project is beyond my "technical competence" is because I have been assigned responsibility for "making it work". My primary competence is in mechanical, not electrical systems. However, I am learning the process and will hopefully be able frame my question a little more accurately.

I would like to move a set of three stepper motors. I intend to send a command over ethernet ("step 200" for example) and have one of the motors move 200 steps. To do this I need a device to convert the command into a pulse sequence for the step motor driver. Basically this would be a pulse generating device. I have drivers and motors sized for the application and my only remaining question is how to generate the pulse sequences for the drivers.

So, what I am looking for is something I can send commands via ethernet which will produce a series of pulses for my drivers. Any idea on how to go about this?

 

[blueroomelectronics]

Why would you me assigned such a task?
Does your project have a budget? Do you want something custom made or plan to DIY?
Does it have to be Ethernet?

 

[Aberdeen57]

Well, I was assigned the project because "somebody's gotta do it" and I was available! Also, it is definitely an interesting project. Budget-wise, it is a whatever-it-takes style though I would prefer to go as cheap as we can. Much of the work has been DIY for other components: solenoids, pressure regulators, switches, sensors, etc and I don't mind getting my hands dirty. On the other hand, if I can purchase something that does it for me, that is often more reliable and cheaper in the long run.

Regarding the ethernet, the answer is "yes-ish." The actual assembly will not have a local computer but is accessed by ethernet (this is already in place for the pneumatics control system and data logging aspects). So ethernet is available and simple to use for it. However, I do have analog and digital outputs available as the assembly (these are controlled over ethernet and some of the channels are being used for the other components in place). So, if there is some way to use the analog or digital signals that would be fine as well.