Stepper motor control

[Ilkka]

Hi,

We are using NI-USB multi function DAQ cards, NI-DAQmx and Measurement Studio.

A next project might be a closed loop control where we would like to control many stepper motors (max. 20). Is there any nice way to make the stepper motor controllers by C# and Visual Studio? Maybe I must make a wrapper around NI motion software library.. or something..?

What driver software we need? What new hardware?

The closed loop controller's cycle time is not critical;  a few hertz is OK..

BR,
Ilkka

[Marco_Brauner]

Hi, it depends which HW-Platform you want to use.

There are basically two possibilities. 

1)  PCI- or PXI-Card programmed with NI-Motion --> C-API can be use in C#/C++-Projects

2)  NI-RIO based Softmotion System, programming with LabVIEW (FPGA) / System can be interfaced via C-API

for 20 axes you need a couple of Motion-Cards or a cRIO-Chassis + Expansion Chassis loaded with motion modules + the drives for 20 axes (depends on the power of the steppers)

Marco Brauner NIG

[srm@viewpointusa.com]

speed control or position control?  what is your feedback mechanism?

[Ilkka]

Hello Stu,

A simple position control is enough.

The feedback: We would like to balance and tune a big diesel engine. We are measuring cylinder pressures and some other parameters. Based on that we would like to mechanically push some parts affecting to fuel injection. A linear stepper motor accutuator is maybe a good solution for that..

The maximum twenty stepper motors is related to a cylinder count of the engine; one stepper motor per cylinder.

BR,
Ilkka

[srm@viewpointusa.com]

i would solve this with a cRIO chassis and FPGA control of step and direction to stepper motor controller that can use step and direction input.  then implement a TCP/IP protocol to control/monitor it from C.  the pressure feedback could be incorporated into the cRIO as well.

one chassis, one digitital module, one analog module.

i have created this kind of application for stepper control several times.

[Ilkka]

Yes.. thanks a lot. I will check the cRIO solution for driving the actuators. I found also an idea, that it is possible to make a communication link between the C#/.NET application and cRIO with a help of shared network variables.

I will surely make the feedback control algorithms into the existing C# application. It contains many years of work and I am not ready to transfer those into cRIO. (I have no experience of it :-)).

Have a nice day,

Ilkka