Help required for setting up equipment I have

[prad]

Hello everyone!
I am a mechanical engineer by back ground, so I am not at all familiar with the electronic stuff...however, I am required to setup a motion control arrangement for controlling a stepper motor...here are the NI equipment i have:
1) FW 7344(Motion controller)
2) UMI 7764(Universal Motion Interface)
3) DAQ 6036E(Multipurpose Date Acquisition Card )
4) CN 0143(Micro-step drive)(this equipment is NOT from NI)
5) SCB-68
6) BNC-2110(Analog to Digital converter)
i also have a load cell and a LVDT to measure the displacement and load being applied to my specimen.
i'd be very glad if you could give me some sketches of how i might be able to go about connecting these equipment so as to get my motion control setup to work.
i have read through the manuals and from what i could gather from it, i have made the following connections as of now.please see whether i am correct or not.
1) leads from LVDT and Load ceel to BNC-2110 and from BNC-2110 to DAQ card in computer
2) FW 7344 to firewire port in computer and also to UMI 7764
3) UMI 7764 to CN 0143
i have also attached something like a circuit diagram i have made...
any kind of help or pointers would be more than welcome and i'd be much obliged!
THANK YOU VERY MUCH

[prad]

please help!!!

[Buechsenschuetz]

I am not familiar with all the devices you are using (since we make our own interconnection devices to the 7344 motor controllers and own motor drives, and we currently do not use NI data acquisition boards). But I think your set up is basically correct.

The SCB-68 seems to be an interconnetion box providing screw terminals instead of the 68pin connector you find on many NI boards. If your data acquisition board has an 68pin connector I think you can use the SCB-68 to connect your sensors to the board, since the sensors probably don't have a suitable connector.

A feedback from a stepper motor to a stepper motor controller such as the NI7344 is not absolutely required. Usually the motor manufacturers do not provide feedback devices such as incremental encoders on their motors, although some can supply them with encoders mounted. You can also use third party encoders and couple them mechanically to the drive (i.e. they do not necessarily couple to the motor shaft directly, they can also be attached somewhere else in the drive depending how precise you have to determine a certain position). You can also use linear encoders with quadrature output if you want to check the position of a linear motion stage driven by your motor. The feedback device is connected to the encoder terminals in the UMI box which feeds its signals to the 7344 board.

There are many basic articles on the NI site explaining operation and use of encoders and stepping motors.

[Buechsenschuetz]

PS. I just saw that you have drawn a feedback connection from the motor to the drive. There are some more advanced motor drivers which can supervise motion of the motor with a feedback device directy connected to the motor driver, but it is much more common to connect the feedback device to the motor controller (the NI7344 board in this case).

[Brian_Beal]

You may want to tell us what you want your system to do. I am not sure what feedback you would be putting back to your driver, as feedback usually goes to the motion controller. You don't need the SCB-68 if you are using the BNC-2110.

[prad]

thankyou for your prompt replies.
i am actualy attempting to build a loading frame for applying loads to a very small specimen. since the applied loads are going to be very small, i wonder whether a feedback is essential or optional for me. i do believe, however, that since i will be using a stepper motor, i might just be able to afford neglecting the inclusion of encoders for feedback.
i would be glad if you could comment on the attached diagram and kindly advise as to how i might improve on the conections i have made. the idea i have in mind is to measure the load applied by the motor using the load cell and also determine the displacement using the LVDT....thereafter, i would want to record the data using an A to D in a computer. the spring has been included in order to control the process of loading the specimen...the whole arrangement is intended to perform similar to a Universal Testing Machine, albeit in a mucu smller scale....
from your response to my last message, i am guessing that the SCB-68 is not of much use to me.....i would also be glad if you could kindly tell me the difference between the "Digital I/O" and "Motion I/O" terminals on the FW7344... currently, i have connected the UMI 7764 to the Motion I/O terminal of the FW7344 and have not figured out how i might use the Digital I/O terminal at all....kindly do enlighten regading that matter too...
once again , i'd like to thank you all very much for your time, patience, help and support....

[Buechsenschuetz]

You do not need necessarily a feedback for a drive. However, in some cases this feature will be very helpful. If there is risk that the motor runs against a stop or that the maximum load of the motor is exceeded it will stop moving, but the motion controller still will send step pulses to the motor driver trying to turn it further. A feedback device (and a low setting of following error) will prevent this.

The digital I/O lines are not required for many motion applications. They are used for special control purposes, i.e. switching on and off warning lights, reading the status of input devices (switches) etc. Since any control system using the Windows operating system is inherently non-deterministic (i.e. you can't determine exactly when something happens or when it is supposed to happen) you should not use the digital I/O for anything which interferes directly with your motion control. If you are using limit switches (which is highly recommended to avoid getting your drive into extreme positions which may damage your system mechanically) you ALWAYS should connect them to the limit switches inputs of the UMI box.