Limit Switches interfacing with PCI-7344

I am trying to figure out the best way to calibrate encoders with the PCI-7344 interface card. Should I setup my limit switches to stop the axis at the limit and then reset encoders there or what? Or should I have a home switch somewhere in the center of travel and let Labview reset the encoders at that point? The 7344 card has digital I/O but they are not configured as anything at the moment. I assume there is a vi to do this? What is the accepted way to do this?
Perry

Hi Perry,
What sort of behavior is your motion system going to have? Typically, you would want for one end (if linear) to be the home. So, I would probably approach it that way. But, what is your system going to be like? As for the digital I/O, there is a palette of VIs to handle this within the NI 73XX functions palette. See the pic.
Matt J.

Similar Messages

Position Control of compumotor linear servo table and GV-U6E with PCI-7344

I'm referring PCI-7344 (not 7334).
I have the GV-U6E which is a drive only and does not possess control functionality. the drive only version does not store or use programs. So, serial commands can not be sent through COM port by LabVIEW even though A few basic commands can be emulated.
I am trying to do position control as I mentioned. For example, the motor should move A point to B point exactly with a certain speed. The points must be aboulte position.
I would like you to see the reference comment that I have been contacting with in your website forum.
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000DD490000&USEARCHCONTEXT_CATEGORY_0=_14_&USEARCHCONTEXT_CATEGORY_S=0&UCATEGORY_0=_14_&UCATEGORY_S=0
Regard,
Jin Ho Lee
----- Original Message -----
From:
To:
Sent: Thursday, September 26, 2002 5:00 PM
Subject: Re: (Reference#1549-QYW196) "Position Control of linear servo table and GV-U6E with PCI-7344
>
> Note: Your reference number is included in the Subject field of this
> message. It is very important that you do not remove or modify this
> reference number, or your message may be returned to you.
>
>
> JinHo. Compumotor is a very popular brand, and I know of several customers
> who integrate our 7334 with Computmotor drives. However, when you say that
> the MAX configuration doesn't fit in the compumotor drive settings, are you
> referring to the specs from the 7344? It looks like the 7344 and the
> Compumotor will work well together through a UMI break out box. If you're
> referring to specific commands that the Compumotor receives, I'd have to
> know more about the protocol. If the Compumotor needs serial commands,
> then you can send them through the computer's COM port from LabVIEW.
> Please let me know exactly what kind of configurations you're trying to
> set. The 7344 can be completely configured in MAX and LabVIEW.
>
>
> Best Regards
>
> Kyle Voosen
> Applications Engineer
> National Instruments
> http://www.ni.com/support
>
> ------------------------------------------------------------------------------
>
> Problem Description :
> "Position Control of compumotor 406LXR linear servo table and GV-U6E(motor
> drive) with PCI-7344"
>
> "Since I had the answers referring:
> http://exchange.ni.com/servlet/ ProcessRequest?RHIVEID=101&RPAGEID=135&
> HOID=506500000008000000DD490000& USEARCHCONTEXT_CATEGORY_0=_14_&
> USEARCHCONTEXT_CATEGORY_S=0& UCATEGORY_0=_14_&UCATEGORY_S=0
>
> Wiring step was done well. However, I still have a problem that MAX
> configuration doesn't fit in compumotor drive settings. Therefore, the
> setup is shown below, and I want to know how I can set up PCI-7344
> configuration in MAX or LabVIEW VI.
>
>
> -----------------------------------------------------
>
> Uploaded from device address 0
>
> Gemini GV Servo Drive Setup
>
>
>
> Motor Setup
> DMTR 1703
> Motor ID (406-x-LXR-M-x-D13-x-x-x-x-E5-x-x-x)
> DMTIC 2.48
> Continuous Current (Amps-RMS)
> DMTICD 0.00
> Continuous Current Derating (% derating at rated speed)
> DMTKE 17.6
> Motor Ke (Volts (0-to-peak)/krpm)
> DMTRES 10.10
> Motor Winding Resistance (Ohm)
> DMTJ 119.300
> Motor Rotor Inertia (kg*m*m*10e-6)
> DPOLE 1
> Number of Motor Pole Pairs
> DMTW 40.5
> Motor Rated Speed (rev/sec)
> DMTIP 7.40
> Peak Current (Amps-RMS)
> DMTLMN 3.4
> Minimum Motor Inductance (mH)
> DMTLMX 3.4
> Maximum Motor Inductance (mH)
> DMTD 0.000000
> Motor Damping (Nm/rad/sec)
> DMTRWC 0.23
> Motor Thermal Resistance (degrees Celsius/Watt)
> DMTTCM 20.0
> Motor Thermal Time Constant (minutes)
> DMTTCW 0.33
> Motor Winding Time Constant (minutes)
> DMTAMB 40.00
> Motor Ambient Temperature (degrees Celsius)
> DMTMAX 90.00
> Maximum Motor Winding Temperature (degrees Celsius)
> DHALL 1
> Disable Hall Sensor Checking
> DMTLQS 0
> Set Q Axis Inductance Saturation
> DMTLDS 0
> Set D Axis Inductance Saturation
> DTHERM 0
> Disable motor thermal switch input
>
>
>
> Drive Setup
> DMODE 2
> Drive Control Mode
> DRES 8400
> Drive Resolution (counts/rev)
> DPWM 16
> Drive PWM Frequency (kHz)
> SFB 1
> Encoder Feedback
> ERES 8400
> Encoder Resolution (counts/rev)
> ORES 8400
> Encoder Output Resolution (counts/rev)
> DMEPIT 42.00
> Electrical Pitch (mm)
> SHALL 0
> Invert Hall Sensors
> DMTLIM 1.5
> Torque Limit (Nm)
> DMTSCL 1.5
> Torque Scaling (Nm)
> DMVLIM 119.000000
> Velocity Limit (rev/sec)
> DMVSCL 119.000000
> Velocity Scaling (rev/sec)
>
>
>
> Load Setup
> LJRAT 0.0
> Load-to-Rotor Inertia Ratio
> LDAMP 0.0000
> Load Damping (Nm/rad/sec)
>
>
>
> Fault Setup
> FLTSTP 1
> Fault on Startup Indexer Pulses Enable
> FLTDSB 1
> Fault on Drive Disable Enable
> SMPER 8400
> Maximum Allowable Position Error (counts)
> SMVER 0.000000
> Maximum Allowable Velocity Error (rev/sec)
> DIFOLD 0
> Current Foldback Enable
>
>
>
> Digital Input Setup
> INLVL 11000000
> Input Active Level
> INDEB 50
> Input Debounce Time (milliseconds)
> INUFD 0
> Input User Fault Delay Time (milliseconds)
> LH 0
> Hardware EOT Limits Enable
>
>
>
> Digital Output Setup
> OUTBD 0
> Output Brake Delay Time (milliseconds)
> OUTLVL 0100000
> Output Active Level
>
>
>
> Analog Monitor Setup
> DMONAV 0
> Analog Monitor A Variable
> DMONAS 100
> Analog Monitor A Scaling (% of full scale output)
> DMONBV 0
> Analog Monitor B Variable
> DMONBS 100
> Analog Monitor B Scaling (% of full scale ouput)
>
>
>
> Servo Tuning
> DIBW 1500
> Current Loop Bandwidth (Hz)
> DVBW 100
> Velocity Loop Bandwidth (Hz)
> DPBW 40.00
> Position Loop Bandwidth (Hz)
> SGPSIG 1.000
> Velocity/Position Bandwidth Ratio
> SGIRAT 1.000
> Current Damping Ratio
> SGVRAT 1.000
> Velocity Damping Ratio
> SGPRAT 1.000
> Position Damping Ratio
> DNOTAF 0
> Notch Filter A Frequency (Hz)
> DNOTAQ 1.0
> Notch Filter A Quality Factor
> DNOTAD 0.0000
> Notch Filter A Depth
> DNOTBF 0
> Notch Filter B Frequency (Hz)
> DNOTBQ 1.0
> Notch Filter B Quality Factor
> DNOTBD 0.0000
> Notch Filter B Depth
> DNOTLG 0
> Notch Lag Filter Break Frequency (Hz)
> DNOTLD 0
> Notch Lead Filter Break Frequency (Hz)
> SGINTE 1
> Integrator Option
> SGVF 0
> Velocity Feedforward Gain (%)
> SGAF 0
> Acceleration Feedforward Gain (%)
> -----------------------------------------------------
>
>
> Regards,
> JinHo"
> NI Software :
> LabVIEW version 6.0
> NI Hardware :
> Motion Control device PCI-7344
> Driver Version :
> no
> OS :
> Windows 2000
> CPU :
> Pentium
> RAM :
> 128
> Vendor :
> DELL
> Customer Information :
> Jin Ho Lee
> North Carolina State Univ.
> US
> [email protected]
> Ph: (
> 919
> )
> 512-9929
>
>

Yes, we used an NI PXI-7344 motion control card with an NI UMI-7764 box connected to a Gemini GV-U12E servo drive. (which is a drive only.)
We did positional control in absolute position mode.
I can send you an AutoCAD schematic detailing how to connect the UMI-7764 to the Gemini GV servo drive.
In regard to the Rs232 interface to the GV servo drive,
the GV drive only model is "configurable" not "programmable". You can create unique GV configuration files with Compumotor's Motion planner then download the configuration via Rs232 using LabVIEW as desired. Or, using LabVIEW via Rs232 you can change individual GV drive parameters on demand,
or use the GV's two analog outputs back to LabVIEW's analog inputs to measure commanded motor current or torque, etc.etc.etc

Position Control of compumotor 406LXR linear servo table and GV-U6E(motor drive) with PCI-7344

Since I had the answers referring:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000DD490000&USEARCHCONTEXT_CATEGORY_0=_14_&USEARCHCONTEXT_CATEGORY_S=0&UCATEGORY_0=_14_&UCATEGORY_S=0
Wiring step was done well. However, I still have a problem that MAX configuration doesn't fit in compumotor drive settings. Therefore, the setup is shown below, and I want to know how I can set up PCI-7344 configuration in MAX or LabVIEW VI.
;Uploaded from device address 0
;Gemini GV Servo Drive Setup
;Motor Setup
DMTR 1703 ;Motor ID (406-x-LXR-M-x-D13-x-x-x-x-E5-x-x-x)
DMTIC 2.48 ;Continuous Current (Amps-RMS)
DMTICD 0.00 ;Continuous Current Derating (% derating at rated speed)
DMTKE 17.6 ;Motor Ke (Volts (0-to-peak)/krpm)
DMTRES 10.10 ;Motor Winding Resistance (Ohm)
DMTJ 119.300 ;Motor Rotor Inertia (kg*m*m*10e-6)
DPOLE 1 ;Number of Motor Pole Pairs
DMTW 40.5 ;Motor Rated Speed (rev/sec)
DMTIP 7.40 ;Peak Current (Amps-RMS)
DMTLMN 3.4 ;Minimum Motor Inductance (mH)
DMTLMX 3.4 ;Maximum Motor Inductance (mH)
DMTD 0.000000 ;Motor Damping (Nm/rad/sec)
DMTRWC 0.23 ;Motor Thermal Resistance (degrees Celsius/Watt)
DMTTCM 20.0 ;Motor Thermal Time Constant (minutes)
DMTTCW 0.33 ;Motor Winding Time Constant (minutes)
DMTAMB 40.00 ;Motor Ambient Temperature (degrees Celsius)
DMTMAX 90.00 ;Maximum Motor Winding Temperature (degrees Celsius)
DHALL 1 ;Disable Hall Sensor Checking
DMTLQS 0 ;Set Q Axis Inductance Saturation
DMTLDS 0 ;Set D Axis Inductance Saturation
DTHERM 0 ;Disable motor thermal switch input
;Drive Setup
DMODE 2 ;Drive Control Mode
DRES 8400 ;Drive Resolution (counts/rev)
DPWM 16 ;Drive PWM Frequency (kHz)
SFB 1 ;Encoder Feedback
ERES 8400 ;Encoder Resolution (counts/rev)
ORES 8400 ;Encoder Output Resolution (counts/rev)
DMEPIT 42.00 ;Electrical Pitch (mm)
SHALL 0 ;Invert Hall Sensors
DMTLIM 1.5 ;Torque Limit (Nm)
DMTSCL 1.5 ;Torque Scaling (Nm)
DMVLIM 119.000000 ;Velocity Limit (rev/sec)
DMVSCL 119.000000 ;Velocity Scaling (rev/sec)
;Load Setup
LJRAT 0.0 ;Load-to-Rotor Inertia Ratio
LDAMP 0.0000 ;Load Damping (Nm/rad/sec)
;Fault Setup
FLTSTP 1 ;Fault on Startup Indexer Pulses Enable
FLTDSB 1 ;Fault on Drive Disable Enable
SMPER 8400 ;Maximum Allowable Position Error (counts)
SMVER 0.000000 ;Maximum Allowable Velocity Error (rev/sec)
DIFOLD 0 ;Current Foldback Enable
;Digital Input Setup
INLVL 11000000 ;Input Active Level
INDEB 50 ;Input Debounce Time (milliseconds)
INUFD 0 ;Input User Fault Delay Time (milliseconds)
LH 0 ;Hardware EOT Limits Enable
;Digital Output Setup
OUTBD 0 ;Output Brake Delay Time (milliseconds)
OUTLVL 0100000 ;Output Active Level
;Analog Monitor Setup
DMONAV 0 ;Analog Monitor A Variable
DMONAS 100 ;Analog Monitor A Scaling (% of full scale output)
DMONBV 0 ;Analog Monitor B Variable
DMONBS 100 ;Analog Monitor B Scaling (% of full scale ouput)
;Servo Tuning
DIBW 1500 ;Current Loop Bandwidth (Hz)
DVBW 100 ;Velocity Loop Bandwidth (Hz)
DPBW 40.00 ;Position Loop Bandwidth (Hz)
SGPSIG 1.000 ;Velocity/Position Bandwidth Ratio
SGIRAT 1.000 ;Current Damping Ratio
SGVRAT 1.000 ;Velocity Damping Ratio
SGPRAT 1.000 ;Position Damping Ratio
DNOTAF 0 ;Notch Filter A Frequency (Hz)
DNOTAQ 1.0 ;Notch Filter A Quality Factor
DNOTAD 0.0000 ;Notch Filter A Depth
DNOTBF 0 ;Notch Filter B Frequency (Hz)
DNOTBQ 1.0 ;Notch Filter B Quality Factor
DNOTBD 0.0000 ;Notch Filter B Depth
DNOTLG 0 ;Notch Lag Filter Break Frequency (Hz)
DNOTLD 0 ;Notch Lead Filter Break Frequency (Hz)
SGINTE 1 ;Integrator Option
SGVF 0 ;Velocity Feedforward Gain (%)
SGAF 0 ;Acceleration Feedforward Gain (%)
Regards,
JinHo

First of all, before connecting the drive to the 73xx controller I would check that the drive and motor configuration works correctly independent from the controller. The Gemini drives have a utility called the Motion Planner that allows you to configure your motor and drive for independent operation so you can test if the motor and drive combination are working by themselves. Refer to page 18 of the Gemini GV installation guide which you can find at the compumotor site or download from:
http://www.compumotor.com/manuals/gemini/Gemini_GV_HW_Install_Guide.pdf
Once you have tested your motor and drive combination, make sure that the drive is configured in torque mode and that the command signal is configured to be sent from the I/O connector and not through RS232 using the Motion Planner. The next step would be to connect the 7344 through the UMI-7764 breakout box in the following order:
---- UMI7764 GVU6E
---- AOut Cmd+ (pin23)
---- AOGnd Cmd- (pin24)
---- InhOut Enable- (pin2)
---- +5V Enable+ (pin24)
7344 --> EncA AX+ (pin8)
---- EncA- AX- (pin9)
---- EncB BX+ (pin10)
---- EncB- BX- (pin11)
---- Index ZX+ (pin12)
---- Index- ZX- (pin13)
---- +5V Encoder +5V (pin5)
Verify that your enable line is connected in an open collector mode (as shown in the diagram above). Our inhibit outputs can sink current but not source it so if your enable line is not behaving properly you want to make sure that the +5v supply you are suing for the UMI can source enough current for your enable line to work. Consult Compumotor on the specs of their enable switch.
Once the connections are done properly, all you need to do is configure and initialize your board for servo operation in MAX and then you can start your tuning process. Refer to the Tuning PID for servos tutorial in:
http://www.ni.com/support/motnsupp.htm
for instructions on tuning your servomotor properly. Also for more information on using MAX, refer to the following tutorial:
http://zone.ni.com/devzone/conceptd.nsf/webmain/081957EE013C7A4586256B92007818E0?opendocument

Using Mitsubishi A500 inverter with PCI-7344

Another question..
I am planning to use PCI-7344 to implement speed control for 7,5 kW
induction motor. Mitsubishi A500 inverter driving the motor seems to
have only speed (frequency) setting input. This axis don't have to make
rapid movements, instead I'm looking for accurate speed and mostly
rotation in one direction only. In the same machine there are
servoaxises with Mitsubishi J2S servocontroller and they work OK.
Movements of servos should be syncronized to the rotation speed of main
axis.. I am asking this because it says in the manual that torque
control should be used.
There are two pulse encoders in that 7,5kW axis. One in the motor and
another in spindle axis after reduction gear. There is also orientation
control/PLG feedback/pulse train unit (FR-A5AP) installed to the
inverter. I'm not sure if that should be used or not.
Tommi

Tommi,
it's a bit easier to tune a system that works in torque mode as typically you only have to tune the position PID loop of the board. That's why torque mode is recommended but that doesn't mean that you can't get good results with velocity drives, too. With a drive that works in velocity mode you will also have to tune the velocity PID loop of the drive and you will probably have to use Vff and Aff parameters of the PCI-7344 to reduce or eliminate the following error.
In order to get very accurate velocity and position control you should use both encoders of your 7.5 kW axis. The encoder that is attached directly to the motor should be configured as secondary feedback device, the other one as the primary feedback device. Please follow this link for further instructions. Also have a look at this tutorial, especially at the "Dual position feedback" paragraph.
Jochen Klier
National Instruments Germany

Has anyone successfully interfaced a PCI-7344 with a Techno-Isel servo box?

I'm specifically interested in the wiring between the UMI-7764 and the Techno-Isel Servo breakout box. Techno-Isel makes good quality stuff but their documentation and support leave something to be desired.

Hello Charles,
Thank you for using our discussion forum. Do you happen to have the pinout for the servo breakout box? I haven't used Techno-Isel's servo systems but if we can find pinouts for this box I'm sure we can determine the appropriate connections. I looked on their website but couldn't find any relevant information.
Regards,
Nipun M
Applications Engineer
National Instruments

How can I control stepping motor with PCI-7344 & UMI-7764? And I want to know the simplest circuit that I can do by myself?

Now I don't want to by commercial stepping motor driver, I want to do it by myself. I want to know the simplest driver circuit to drive and control my stepping motor (+5V 4 phases).

From the 7344's perspective, in open loop stepper mode, the only necessary outputs are the pulse train for steps and a TTL flag for direction. You can also set it for CW/CCW mode, which will output two separate pulse trains: one for clockwise motion, one for counter-clockwise motion.
If you only need to decode the signals into four phases and not amplify them above 5V, then a small IC might work for you (as long as you don't need a lot of current). A reconfigurable FPGA could be programmed to decode the incoming signal and output the four phases pretty easily. However, I honestly believe your best bet is just to buy a recommended amplifier for the motors.
Good Luck
Kyle V
Applications Engineer
National Instruments

About Limit Switch

Hi,All
I use NI PCI-7344,UMI-7764 and servo motor in my project.Now I meet a problem about limit switch----That's PCI 7344 can't detect the limit
switch's status if I set the motor's velocity a little faster(for example,1500RPM).It's very dangerous,my compents are allways hit.If I set the
motor's velocity at 500RPM or 1000RPM,this situation won't happen.
After I diable the Limit Filter in MAX,this situation still happened.My limit switch is producted by OMRON,their type is EE-SX671,they are photomicrosensor.their parameter as followensing distance(slot width):5mm.Response frequency*2:1KHZ min.(3KHZ average).After I
change the photomicrosensor to mechanical switch,the problem still occur.
I am very vexatious,Where is the problem?The Response frequency is not enough?How can I resolve the problem?Pls help me!
Thanks you in advance!
B&R
EnquanLi
Striving is without limit!

Hm, I don't think that increasing the rate of deceleration will help here as in default mode the 7344 executes a HALT when a limit switch is hit (this ignores the deceleration settings). This means that the controller tries to stop the motor as fast as possible. But there are two things you could try:
Improve the PID tuning. Maybe your system is tuned too conservatively and there is some room for optimizing the stiffness of your axis. Please have a look at this link if you need help for tuning your system.
The limits of the improvements that you can achieve with PID tuning are defined by the system stability and the motor torque which is proportional to the current provided by the drive. If your drive runs into a current limit, this will also limit the torque and the deceleration capabilities of your motor. Please check if there is a way to increase the current limit of your drive (make sure that you don't exceed your motor's specs!).
Please note: Increasing the current limits may require some adjustments of the PID parameters.
I hope this helps,
Jochen

Pci 7344 to compact field point

Is it a good idea to switch from using PCI 7344 motion controller card to compact PAC so that I can implement fuzzy motion algorithm to control three axis ac servo motors.
TQ.

If you need higher level control than PID for your motion application NI SoftMotion is highly recommandable. This software module will give you a trajectory generator, a spline engine and a complete motion API and it is independent from the hardware you use.
As a hardware option I would either recommend a cRIO-System with an embedded controller or a cRIO R Series Expansion system with a PXI-7811R in a PXI chassis with an embedded controller running LabVIEW RT. It's mandatory to run the supervisory application on a RealTime target like the PXI or cRIO embedded controllers as it needs to run in synch with the control application on the FPGA.
FieldPoint or Compact FieldPoint is only an option if your control algorithms are allowed to run extremely slow (more than 10 ms control loop rate). Typical motion applications require control loop rates of 1 kHz and above. The cRIO and PXI/RIO solutions support control loop rates up to 100 kHz and should be a much better choice.
The solutions that I have proposed are of course much more complex than using a PCI-7344 motion controller as all the software layers that are present in the firmware of the PCI-7344 need to be implemented in software. Additionally it incorporates LabVIEW RT and LabVIEW FPGA programming. SoftMotion is a great alleviation as you can concentrate on the control algorithm and the rest is done for you. Especially the shipping examples help a lot to get started.
In my opinion SoftMotion in combination with LV RT, LV FPGA and a corresponding target hardware is one of the best and simplest solutions in the market to create your own motion controller with your own control algorithm.
After the release of SoftMotion it took me only one working day to learn the API, setup the hardware and modify an existing example. After that I had a running motion control application.
Everything is done in LabVIEW, even the real-time and the FPGA programming but it's not a good idea to start such kind of a project as a LabVIEW novice.
Best regards,
Jochen Klier
National Instruments Germany

PCI-7344 Servo Command Analog Ouput

Hi,
I am currently working on a project controlling several servos with PCI-7344.
Servo amplifiers are working with +/-10 V. But with the servo's direction command, the polarity of servo command decides the motor's rotation direction.
For an instance, with CCW direction, -10V means the maximum speed in reverse. and 0 means sero speed.
So the problem is how to configure DAC outputs to produce -10V and +10V for full speed and 0 for zero speed.

You have to enable the secondary feedback to the same encoder as the primary feedback. I know it sound crazy but it works. I scared half the maintenance crew to death the first time I tried to run autotune. Then tune manually start with real low values like 1. One of the techs sent the attached file it helped. Oh I found a work around for my stopping problem I break the command line to my drive and have a 100k resistor shorting the command out that takes it to 0 volt and stoppes the motor. Of the hundred plus drive we have in this plant none use torque command. So much for Industry standard :-) Hope this help you.
Attachments:
motion_control_hands-on_servo_tuning.pdf ‏435 KB

PCI-7344 Servo Torque Control

Hi,
Is there any body to have controlled torque with PCI-7344?
I have two servos to keep servo's torque constant as a target value. The target torque can be changed on cerain conditions.
So the servo's torque reaches the target, it shoud be stopped at that postion unless any change in servo's torque happens. If the servo's torque is below the target, it shoud be move forward to get more torque and vise versa also.
Now, I would like to know how to use PCI-7344 axis to control torque.

Hi Choijs,
It's really the motor amplifier that is doing the torque control rather than the motion controller.
Most amplifiers today are current(torque) amplifiers. In addition, a lot of amplifiers can operate in either torque mode, or velocity mode.
Now, the reason why torque amplifiers are also called current amplifiers is that torque is proportional to current. When the motion controller outputs a command voltage, it's up to the amplifier to convert that voltage into current, and it's up to the amplifiers internal control loop to hold that current. Essentially, the amplifier controls the torque via a current transformer. When there is a difference between the desired torque, and the actual torque from the current feedback, the amplifier will adjust the output vo
ltage to accomdate for the difference.
That's probably too much information, but you just need to know that the torque control is actually done at the amplifier level, and when you are using an amplifier in torque mode, all this control is done for you by the amplifier. So, there is nothing the 7344 needs to do.
Another way to think about this is whenever you tell a motor to go to a specified position and stay there (using a torque amplifier). You are doing torque control automatically, since it takes effort to hold a motor at a specific position. The control loop on the amplifier is constantly doing what you have described, without the 7344 knowing what it's doing.
Hope this helps.
Ken Sun
Applications Engineer
National Instruments

PCI-7344 motor interfacing help

Hi,
I've been provided with a PCI-7344 together with a UMI-7764 by my university for my course final year project. My project consist of controlling 1 stepper motor, 3 dc motors and 1 servo motor. Also included is 4 digital proximity sensors. As im still new with motion control cards, I would appreciate it anyone can help guide me.
I'll be using thrid party motor drivers for the stepper motor and dc motors (H-bridge). I know that i'll be connecting the stepper motor output to my stepper motor driver but im confused about where would i get a output for my dc motors. Can i use the digital output for motion i/o (inhibit) to generate a pwm signal for my dc motors or it's possible to connect my dc motor driver to the stepper output? Finally, is it possible to use the digital inputs for the motion i/o (encoder, home switch) with my proximty sensors?
The problem is that i only can use the I/O from the motion i/o port because the SCB-68 that is required for the digital I/O port may not be accessible to me.
Any help and suggestions would be greatly appreciated. Thank you
-Terence

Terence,
the PCI-7344 can control up to four axes. Any combination of 0 to 4 open loop or closed loop stepper motors and 0 to 4 servo motors (always closed loop) is allowed.
I don't see a good way to control 5 motors with this board. If you need PWM signals to control (not to drive!) additional DC motors in open loop mode, you could use two static PWM outputs on the Digital I/O connector (yes, you will need an SCB-68 to access those). These outputs are static. That means, that you can adjust the frequency and the duty cycle in software only so you can't generate trajectory profiles on these outputs.
In general you can't use stepper outputs to control DC motors, as you can't control the duty cycle of a stepper output. All other digital I/O signals are static and can't be used to generate control signals. If you really need to provide PWM signals for you DC motors' drives, you could use an additional counter board like the PCI-6601. Still you won't be able to generate trajectories with this board. If you need to create trajectories for open loop DC motors, it might be a better option to generate analog waveforms on the analog outputs of a mutlifunction DAQ board and use a DC motor drive, that converts an analog input signal to a PWM power signal.
Please note that the 7344 can't drive motors directly, so you will have to use power drives for all axes.
You can use proximity sensors as limit switches with a 7344 but you need to be careful with that. The lilmit switch inputs of the 7344 are pulled up to +5V with 3.3 kOhm. Many proximity sensors switch between +5V and 0V but they typically have a high output impedance, resulting in a voltage divider with the 3.3 kOhm resistor. You may get around this issue by connecting a resistor from the limit switch input to ground to reduce the voltage level when the proximity sensor has switched to low level. This is not a very clean approach and you should use a potentiometer instead of a fixed resistor to find the right value for the resistance.
A much better approach is using a UMI-7774 instead of the UMI-7764, which provides direct connectivity for proximity sensors.
I hope this helps,
Jochen Klier
National Instruments

CPU-Usage during control of a DC Motor with the PCI-7344 board?

Hello!
I want do control a DC-motor (no stepper motor). Now i´m using the PCI-6527 board and simulating the delay between "high" and "low" on the Simulate-signal-vi. This works fine while no other process on the PC is running. The CPU-usage rises up to 100%. Is it possible to use the PCI-7344 board for controlling my DC-motor and having enough CPU resources to do other things like capturing pictures with a cam at the same time? The CPU is a Pentium 3 1Ghz.

The PCI-7344 is a perfect solution for your problem. This board is designed for motion control applications and it's running everything on its own DSP and CPU:
Trajectory Generation, PID control, limit switch monitoring and so on.
Thus the PC's CPU is free for other tasks. Please note that you need a position feedback signal from a quadrature encoder.
Best regards,
Jochen Klier
National Instruments Germany

Problems with a PCI-7344 motion controller

Hi all,
I've run into a weird problem with a NI PCI-7344 motion controller, where I
have a program that provides the motion control for my program that works
reasonably well, but when I make minor changes gets motion errors. The changes
are not specifically to the motion parts, just changing a couple of globals
that provide communication with another part of the program (and another piece
of hardware). The errors I get indicate that I am trying to enable limits
switches at the wrong time in my program. I will add that I do not get any
errors when I go through the program in debug mode
Tnx,
P.W.Monroe

The portion of my program that gets the errors uses the "Flexmotion" Find Home
and Find Index routines, which are built into the 7344 controller. In the
exampes for using these VIs, they are followed by a loop that has a VI that
monitors the status of these VIs for completion, both move complete and Home or
Index Found. The globals that I mentioned are being used to terminate the loops
if an error condition occurs elsewhere, and do not cause the program to do
anything other than terminate looking at the status and then go into a wait
loop. It crashes when it goes into the loop when I substitute a different
global, which is baffling to me, as they aren't triggering something that would
result in a race condition.

Limit switches with MID-7604

I am trying to integrate a forward and reverse limit switch with a linear actuator. I need the actuator to find the forward limit, offset from the switch enough the disengage the switch, stop there while another task is occuring, then retract to the reverse limit, and finally offset from the reverse switch enough to disengage the switch.
I'm able to get this procedure to work one time through when the driver is just turned on, but after it's gone through the procedure more than once, the actuators no longer offset. I'm defining the offset amount in Measurement and Automation Explorer. It appears that the "find reference" VI longer finds the forward and reverse limits after the first time because if I probe the output of the "check reference" VI, the value is false even when the actuator has stopped on the limit switch.
Is there something I need to clear after each cycle? Any suggestions would be great.

Hello,
Do you have any data acquisition board? You will need one to capture the signal and process in labview.
If you don´t have one, you can search in NI website. The NI has several models.
Best regards.

Windows 2000 upgrade from win98--will i have problems with my pci-7344, pci 6110e & ni5411?

I am running win98 with my Labview 5.1. It running fine, but I would like to upgrade the os to windows 2000.
When I was running a check of the hardware, win2k said that the following hardware may not run:
pci-7344, pci-6110 & ni-5411.
will i need new drivers?
will i run into any problems?
any suggestions?
thanks!
Byron Golden
Allied Geophysical Labs
U of Houston

Byron,
You should not have any problems when you upgrade your OS. Depending on what driver versions you have for that hardware, you may want to go ahead an upgrade your drivers anyway, though. The drivers for these devices are all available for free from our website at:
Current Driver Versions
http://digital.ni.com/softlib.nsf/webcategories/9AD71162B755F0E786256BBC005F001A?OpenDocument&node=132060_US
Try that and let me know if you have any trouble.
Regards,
Scott R.
Applications Engineer
National Instruments

Limit Switches interfacing with PCI-7344

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