How do i Model the MID 7654

I am trying to produce a simulink model in Matlab of my force control system ( A servo motor , connected to the MID 7654, which is connected to the NI 7344 flex motion board, A force sensor connected to ADC-1 closes the loop). In order to complete the system transfer function i need to know what output voltage is being applied across the servo motor as it is this (if my understanding is correct) , which determines the current through the motor, the growth rate of which is goverend by the motor inductance. I know the NI 7344 outputs a signal between +/-10V, how is this acted upon by the MID7645??, the only onfo given in the manual is a current output, surely there must be an accompanying gain applied to the voltage which is then applied to the mot
or which then detemines the current running through the sytem. Any help which could help me better understand the system and produce a model would be much appreciated !.

There is no "characteristic" transfer function for our MID motor controller. That transfer function is going to be the result of the MID in combination with the motor that you are using. The output of the MID is going to be in current. That current is going to be related the current that you select with the MID's jumpers, and the voltage input that the MID receives from the Motion Control Board. This output is characterized by two charts that you can find in the MID's user manual.
MID's user manual
That current output plus the characteristics of your motor should allow you to calculate the relevant transfer function.

Similar Messages

How do i regulate the voltage/current from the MID 7654

I am trying to control a linear motor using flex motion and the MID 7654 power drive, however there are variuos discprencies between what should happen and what is happening:
1) I have configured AXIS one as an open loop stepper, i have specified a target postion (1000) counts, Max reports movement complete however the power amplifier is outputing 50 volts as soon as motion is started and after it has finished. ( should this value not vary with varying speed and positions, i have tried and it does not ???)
2) If configuring the axis as a servo loop and specifying KP as zero, i still get a max output, should this not be zero also.
3) Follow intiialisation i get maximum output from the power amp. I realise the ax
is must be energised and a holding torque applied, but this is causing the motor to shoot off ! why ??
Any help or advice would be much appreciated !!!!

Hello,
MID 7654 is a servo amplifier and will only work with servo motors. Do not expect anything reasonable to happen when the axis is configured as a stepper instead of a servo as it's not the intended use.
After you configure the axis as a servo you need to tune the PID loop parameters. Until you do that the current sent to the motor will not be correct and you might see unexpected movement on your axis.
Also make sure the current settings of the amplifier matches the ones in the motor's spec sheet.
Hope this helps!
Regards,
Yusuf C.
Application Engineering
National Instruments

Can I Connect a 6-wire Unipolar Stepper Motor to the MID-7654/7652?

I am trying to connect a 6-wire unipolar stepper motor to the MID-7654/7652 motor driver and was wondering how the wiring would work on that?

The connector is simply a pass-through for the signals generated by the motion controller card for hooking up to a separate driver compatible with stepper motors. It would be used if you had a combination of servo and stepper motors in your system used in conjunction with separate servo and stepper drives.
-AK2DM
~~~~~~~~~~~~~~~~~~~~~~~~~~
"It’s the questions that drive us.”
~~~~~~~~~~~~~~~~~~~~~~~~~~

Axis resource allocation and the MID-7654

Hello All,
I am currently transferring my application over to use the MID-7654 instead of third party drives. Below is the start up process I am using to allocate the axis resources:
//kill and disable all axes
flex_stop_motion(boardID,0,NIMC_KILL_STOP,0x000F);
  flex_enable_axes(boardID,0,3,0x00);
//unmap all axis resources
  flex_config_axis(boardID,NIMC_AXIS1,0,0,0,0);
  flex_config_axis(boardID,NIMC_AXIS2,0,0,0,0);
  flex_config_axis(boardID,NIMC_AXIS3,0,0,0,0);
  flex_config_axis(boardID,NIMC_AXIS4,0,0,0,0);
//map encoder resources to axes 1 and 2
  flex_config_axis(boardID,NIMC_AXIS1,NIMC_ENCODER1,0,0,0);
  flex_config_axis(boardID,NIMC_AXIS2,NIMC_ENCODER2,0,0,0);
  //enable axes 1 and 2
u8 mask = MASK1|MASK2;
status = flex_enable_axes(boardID,0,3,mask);
Basically, I want to use the encoder resources for each axis for position/velocity monitoring and control the analog outputs directly to change the torque of the motors. Since my impedance control software is closing the position and velocity loops, I do not want to use the PID controller onboard the PCI-7344.
The above code worked fine with the third party drive. However, after starting up my application with the MID drive, all of the orange inhibit LEDs turn on and remain that way (I assume it is to do with killing and disabling all of the axes and not mapping output resources to them). Since I wasn't previously using the inhibit output from the motion controller, my application worked fine with the third party drive (I was still able to read the encoder feedback information).
Also, when I was using the MAX '1-D interactive' interface to verify my encoder feedback, if I move either encoder immediately after initialization the 'Motor off' and 'Following error' lights turn red. I assume this is due to the encoder moving without a command sent from the motor).
Can anyone see any problems with the above code segment or suggest an initialization procedure that would solve my problems. Or if all else fails, is it possible to control the inhibit signals directly to enable/disable the axes on my own?
Wow... I certainly rambled on a bit there.... If you need clarification on any points let me know. Also, I am on a bit of a time crunch, so a prompt reply would be greatly appreciated.
Thanks,
Chad

Chad,
I'm a bit astonished that you don't want to use the PID controller on the board. Onboard PID control is one of the main reasons why you would like to use a motion control board instead of a simple multifunction I/O device. The onboard PID loop of the 7344 can run with up to 16 kHz with very low jitter whilst using the DACs directly from your host application will result in a control loop with less than 200 Hz and a high amount of jitter - even if you were using a real-time OS. This will result in poor control behavior.
This is caused by the architecture of the board. The DACs can be controlled directly by the DSP on the board with high rates in a determenistic way but the host can access them only through the board's µController that runs the host communication in 5 ms cycles that can't be synchronized with the application on the host PC. So for this usecase a combination of e. g. a PCI-6229 (multifunction DAQ board with 4 analog outputs) and a PCI-6601 (4 counters with direct quadrature encoder connectivity) would do a much better job at even a lower price.
With this said I really can't reccomend the usage of a PCI-7344 as a pure I/O-board. Please provide some information why you want/need to choose this approach. There are a lot of options to build customized motion control systems. Please follow this link for some further information.
A key feature of every control system is deterministic behavior so you will need to run your application on a real-time OS. Otherwise you won't be able to get a reliable control behavior.
I can give you some more specific advice if you post some background information about your application.
Best regards,
Jochen Klier
National Instruments Germany

How do you change the midi channels of a region?

Lets say i have a region recorded on midi channel 1, how do I change the notes to be midi channel 2? Thanks

Depends.
First of all, are you talking about a MIDI region or an Audio region (Audio regions can "be on a MIDI channel", so to speak, if they contain controllers, i.e., volume, pan, etc.).
So let's say you're talking about MIDI regions for now.
The first order of business is to recognize that the actual channel of the MIDI events contained in the region is determined primarily by the MIDI channel that your controller is sending on. For simplicity sake, let's say your controller sends on channel 1, and the track you're recording on is set to play MySynth on channel 1.
If you're wanting to change the channel from 1 to 2, chances are you want to do this to assign this part to play a different sound on a multi-timbral synth. Let's say that the MySynth object -- as seen in the Environment -- is indeed a multi-timbral synth. If the synth selected for that track is currently assigned to play MySynth 1 (i.e., channel 1), just change it to MySynth 2 (from the track's menu).
Now, if you opened the Event Editor, you'd see that the channel of the MIDI data is still on channel 1! This is normal. Logic is able to "channelize" the data when you select a destination instrument that is on a different MIDI channel from the one that the data was recorded on. So if your track is now set to play MySynth 2, you can go into the Event Editor all day and change the MIDI channel of the data, but it will still be channelized to channel 2 because that track is assigned to play MySynth on channel 2.
There are many many reasons why you might still want to change the MIDI channel of the data in the Event Editor despite the channelizing that goes on. But without going into a whole shpiel about these kinds of applications, just know that the primary way to change the MIDI channel is to select an instrument on the desired MIDI channel.

How can I hear the MIDI Out through my computer?

A basic question, I'm sure, but my MIDI controller is sending input to Logic, and Logic is recording the MIDI fine, but I can't work out how to get the Out to come through my computer's speakers. It just says 'no out' in the Transport Bar.
How do I get it so I can hear the MIDI?
Cheers

There is no such concept as "hearing MIDI". MIDI is a control protocol, it doesn't make sound.
To hear sound, you must route the MIDI data to an instrument, which reacts to MIDI messages such as "Play a middle C note" and actually plays itself with it's current patch to make sound.
Select/create a software instrument track. Choose which instrument you want on it. Now that instrument will play when you send MIDI data to it, and the resultant audio output will go to whatever audio interface you have chosen in Logic, whether your internal speakers, or whatever other audio interface you may be using.
I really recommend starting with the Getting Started manual to illustrate these basic concepts if you are new to this.

How do I change the midi staff style from piano (i.e. bass and treble clef) to a drum score?

Is there a way to change the staff style in Logic Pro 9 from piano to drums?
In the score window I have tried selecting layout then staff styles... then clicking the downward arrow next to piano and changing to drums (but there is no box to select apply changes), I then back out and it still displays and uses a piano score.
Also is there some sort of setting I can apply so that Logic acts with some Logic... i.e. if I'm using a drum audio instrument then the score editor automatically changes to a drum score, similarily with bass and bass clef?

If I understand you write, you are looking for remapping of the incoming MIDI messages.
So your MIDI Drum Kit is connected to your Mac and sends MIDI messages
A few question:
What MIDI Note message is your drum kit sending when you hit the kick drum, or lets ask, what note "should" it send? Record a MIDI Region while playing your kick drum. Open the Piano Roll Editor and look up what MIDI note that is.
Can you change the assignment on your Drum Kit, i.e. set what MIDI note is send by each drum kit peice?
What MIDI Instrument are you using for the drums in GarageBand?
Do you know what MIDI note is assigned to the Snare sound (D1 ?)
A the end it is about matching the sending note (send from the kick drum) to the expected receiving note (assigned to the snare sound). Changin Cable wouldn't do anything. Either you have to change the receiving mapping (hard to do in GB), or change the sending not from the Kick Drum (should be possible).
Hope that helps
Edgar Rothermich
http://DingDingMusic.com/Manuals/
'I may receive some form of compensation, financial or otherwise, from my recommendation or link.'

How do I include the MIDI sound database in my JAR?

Do I just put it in the Jar and type include soundbank or something?

EJP wrote:
MIDI not working on other PC's.And still no SSCCE.
db

How do I stop the Midi Timeout error?

My M-Audio keystudio 49 Midi Keyboard, & MPD 26 are not being picked up by my Mac. All that I keep getting is "Midi Timeout" everytime my garage band opens. To make things worst, my Garage Band opens abhorrently slow.

I figured it out for mine, I'm not sure if it's the same for you, but all I had to do was open my Pro Tools then Garage Band program. I hope that helps.

How do I use the analog input (ADC) to drive a motion profile in MAX

We are trying to use an anolog input signal from a DAQ card to control the motion contol axis. For now, we want the motor speed to follow a sinusoidal voltage waveform, and later on, we will be using a more complex velocity profile.
In order to accomplish this task, we have searched the user forum, and found information suggesting to operate the servo motor in 'slave' mode under the 'gearing' option. Therefore, we have set the Gear Master to 'ADC Channel-1', Mode set to 'absolute', Gear ratio 1:1, and provided the sinusoidal voltage (+/- 5V, 3 Hz) to the AIN1 connector on the MID-7654 controller. When using the 1-D Interacitve 'single axis' control panel, the motor runs at constant speed in one direction only. It does not react to the sinusoidal speed profile request as we expected.
How do we 'turn on' the 'slave' mode in MAX? Please talk us through the necessary steps and settings? Thanks.
Staffan

Staffan,
you can configure and enablethe Gearing mode in MAX and it should be activated after saving the settings and initializing the board. In 1D-Interactive you can't use Gearing. For better flexibility I recommend not using MAX for configuring and enbling Gearing. You better should do this in your application.
In fact there is a perfect LabVIEW-example that ships with the NI-Motion driver (Master Analog Input - Slave Axis Gearing.vi)
I hope this helps,
Jochen Klier
National Instruments
Message Edited by Jochen on 10-02-2007 08:37 AM
Attachments:
gearing.jpg ‏162 KB

How do i extend the bandwidth of my system

The control problem I am having is extending the bandwidth of a force control system. The system is used to apply mechanical load to bone to facilitate research into Osteoporosis. The following concisely describes the system and the different things I have tried to solve the problem,. I imagine it is quite lengthy compared to the usual questions but any advice you have to offer to a Mechanical engineer would be much appreciated.
System Description:
I am using Labview (with Flex motion) to program the NI 7344 motion control servo board (PID update rate of 62.4 micro-seconds). This output signal is then amplified by the MID 7654 power amplifier, supplying current to a Voice coil (this can be considered as a Linear DC motor with a bandwidth of 40Hz). This applies the force to a bone sample. Feedback is then provided by a load cell and connected to the ADC feedback channel of the servo board. (For full specs of all mentioned components please refer to the web links which are listed at the end of this email!)
Problem description:
After optimally tuning the PID characteristics and defining the amplitude and pre-load, I can successfully control a continuous, sinusoidally varying force (frequency 1Hz), however when I try to increase the frequency to 10Hz, the amplitude of the output waveform is marginally reduced�i.e. there is attenuation. I know that the bone sample is not viscoelastic enough to act as a low pass filter. The bandwidth of the Voice coil is not a limiting factor either, so�..
How do I extend the bandwidth of this system?
The following Paragraph describes some of the things I have tried, which have had some or no influence. Being a mechanical engineer I would be grateful for any expert advice.
(Note all results have been verified with an oscilloscope where applicable)
Influential Factors:
1) Method of programming.
To generate the wave form a series of points describing one period are written to a circular buffer on the servo board. The points are executed in 10 milli-second intervals and are splined through using a cubic spline algorithm (hence a period described by 100 points gives us a frequency of 1Hz and a 10 point wave gives us 10Hz). All this happens on the servo board in real time. I am confident that although the integrity of the sine wave is reduced at 10 Hz the amplitude is still described within the 10 points and so is not the reason for attenuation. However this does limit the maximum frequency achievable. (I would say the max frequency is about 20Hz)
2) Redefining the resolution of the of the ADC Feedback
The 12 bit ADC feedback channel is scanned at a rate of 50 micro seconds (faster than the loop update rate which is 62.4 micro-seconds). Initially the voltage range was specified at -/+ 10 V giving 20/(2^12) Volts per significant bit, however I noticed that when I increased the resolution to the max possible by changing the range to 0-5 V (giving 5/(2^12) volts per significant bit), the amount of attenuation was reduced, however there was still some attenuation there. This begs another question why would this factor improve the frequency response???
3) PID characteristics
The system gives an optimum step response when using only a pure integral term and setting Kp= 0, Kd= 0. It seems as though the fastest step response is limited to about 6 milli-seconds. The system is fine tuned and any slight increase in the integral term results in immediate instability. Therefore there is no scope to improve the system bandwidth by altering the PID characteristics.
Can you offer me any expert advice?
Considering this information, what would you advise? Do I need a board with a faster loop update rate ?, I have considered using Labview Real Time, which offers a board with a 26 KHz update rate as apposed to the 16Hz (62.4 micro-seconds) provided by the current board). Do I need to use different control algorithms as apposed to PID, if so which ones???
Any help or advice you have to offer would be much appreciated and could help in the battle against osteoporosis. Should you require more information or would like to speak to me send me an email and I can answer any further questions or give you a ring.
Regards Duncan Webster
Email: [email protected]
Product specs:
Servo board:
http://www.ni.com/pdf/products/us/4mo636-637.pdf
Power amp
http://www.ni.com/pdf/products/us/4mo642-643.pdf

Hi Duncan,
i'm sorry that this answer took this long, but i think a constructive answer which takes a long time is better than a useless answer in a short time....
For the following thought-provoking impulses we have to consider the signal-change when increasing the frequency. The points which describe the signal get streched over the period. Increasing the frequency enlarges the distance between the points.
a) The spline algorithm could be the problem here hence the signal does not correctly pass through the points anymore with increased frequency. Therefor the amplitude decreases with increased frequency. Perharps another kind of spline algorithm can be helpful.
b) Another point can be the control deviation. Since a feedback control system needs a devia
tion for the control, the deviation gets larger when increasing the frequency of the controlled loop. Maybe the control loop has to set the desired value when already getting to a new point. So the signal could get "washy" and the maximum amplitude is reduced.
In this case, the "Velocity Feedforward"-parameter could be of use. This parameter is to use with caution for it can have similar effects like a too high chosen integral term.
c) You can try to set the 7344 to circular contour. Therefor use 2 axis where you use the second axis as dummy (open step). There is a major disadvantage in this setup: since you use 2 axes at the same time, the 7344 can update each axis only with 125 microseconds. But perharps this is sufficient. Either way the parameter of the control loop have to be adapted (integral term reduced).
d) If the 125 microseconds describend in c) is insufficient, you can try to test it with a 7352. The 7352 can handle 2 axis at a time with a update rate of 62.5 microse
conds for each axis.
I hope this answer helps you in solving your rather special issue.
-Norbert
NI Germany
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

Where are the MIDI Apple Loop files stored?

Am I the only one that wonders where the MIDI files are stored for GarageBand? The ones installed by iLife, the Jam Pack additions and any custom MIDI loops I create are nowhere to be found. Spotlight doesn't show any MIDI loop name I search and I have spent an entire day scrounging through just about every folder on my Mac looking for these puppies! Does ANYONE know where these files are stored?!!?

Alright, then...
You appear to be correct, in as much as the developer specification for the Core Audio Format has provisions for a "MidiChunk". Thank you so much for at least pointing me in the right direction. I still couldn't find any explanation for this issue on the website you referred me to (and had previously visited), but I did find a small explanation in an obscure Apple Tech Document.
What I would still like to know is:
1. How do you access the MIDI data within the .caf files? I haven't found any application that will extract or access that data.
2. When I create custom MIDI sequences within GarageBand and save them to the Loop Library (e.g. a piano track named "hoity-toity-supercilious-wankersequencedeluxe"), they show up in the Loop Browser but I still can't locate the actual file anywhere on my Mac. I know I can just open up a GarageBand file in Logic and then export the MIDI file out from there. But, I would REALLY like to just be able to find the file to begin with and skip that extra stage.
If I could just find the answers to these burning questions. Oh, and (singing) if I only had a brain!
Thanks again for getting me this far!

MID-7654 Current Limits

Hello,
I am using an MID-7654 drive to power DC servo motors with the following specifications:
- Continuous Current: 4.2A
- Peak Current: 21A
- Inductance: 1.92 mH
- Maximum Terminal Voltage: 50V
My original understanding was that the current limit DIP switches on the front panel changed the gain of the system such that a +/-10V input would correspond to the peak current limits (+/-) [Quote from the MID-7654 manual pg 10 - "The MID-7654/7652 varies the gain applied to the input voltage so the maximum input voltage corresponds to a current output equal to the peak current limit, Ipeak."]. Being paranoid like I am, I wanted to verify this thought before doing anything. For current settings of 0.85A/1.7A (cont/peak) I measured a gain of approximately 0.99A/V and for current settings of 1.25A/2.5A (cont/peak) the gain was approximately 1.0A/V (ie: no altered gain). In both cases the output current saturated at the specified continous current limit (for a continuous input voltage).
Based on the above measurements, I have the following questions:
- Do the DIP switches simply change the current limits without altering the actual gain of the MID-7654?
- If this is indeed the case, is there a way to change the gain of the drive such that +/-10V corresponds to a desired peak current range (say 4.2A or 4.9A)?
Thanks,
Chad

Hi David,
I have attached an Excel spreadsheet with the voltage and current measurements I made. I supplied the input voltage by directly accessing the DAC on the PCI-7344. The actual voltage measurements were made from the AOUT block on the back panel of the drive. The current was measured with a DC ammeter in series with the motor, while the output shaft of the motor was fixed in place to prevent motion.
As you can see from the measurements, the motor is not saturating right away and the gain is linear (~1A/V) with a slight DC offset. Voltages higher than those shown in the Excel sheet simply saturated the output current at the level specified by the DIP settings on the front panel. Since the output saturated around the selected limits, I would think that these current measurements are reasonably accurate.
Thanks,
Chad
Attachments:
amplifier_gain.xls ‏20 KB

MID 7654

Hello everybody,
I have been using MID-7654 for like 1.5years for now with the motion controller PCI-7358. I have encountered several problems and I now am controlling 4 different servo motors simultaneously. But today when I powered the system up, the motor connected to the 3rd axis of the MID-7654 wasn't responding to the commands. I opened MAX and saw that when I commanded any thing the motor wasn't moving at all, but the following error was increasing and the axis was killing itself. I tried to assign the axis 5-8 of motion controller to driver and again all axis except axe 3 was working.
Can there be sth wrong electrically inside the driver? Has anyone faced a similar problem? Is there a chance to overcome this problem changing the settings of the axis?
Thanks for all the responses in advance...
Gencer
Solved!
Go to Solution.

Thank you Jochen,
First of all I've never opened a thread with an implicit header like this before but I think this time though I've changed the header the browser sent my query word as a header. I've already tried everything you've offered. I've tried different cables, different motors and also I've verified these components using other axis and they worked.
So as you suspected there would be a very great chance that the MID-7654 has an H/W failure. In that case what can I do, I will check my guarantee situation? Do you think it can be repiared or what?
thanks again...
Gencer

How can i connect the Faulhaber Motor to MID-7654?

How can i connect the Faulhaber Motor (3564 024BC, with Encoder HEDM 5500 B12) to MID-7654?
The Motor has following wires:
A: Hall sensor green; A: Phase brown; B: Hall sensor blue; B: Phase orange; C: Hall sensor gray;
C: Phase yellow; +5V: Voltage red; GND: Ground black
The Encoder has:
5: Channel B; 4: Vcc; 3: Channel A; 2: Channel I (Zero impulse); 1: GND
I don't know how I can connect the encoder to MID-7654 using these wires (what is Encoder Index? Instead of this i only have Channel I !)
Thanks!
WLAN

Unfortunately there are different designators for the encoder signal which NI refers to as encoder index. In your case I am pretty sure that the I channel is identical to encoder index.
Other designators I have found are Z (z-ero signal) and R (r-eference signal) for the index signal.
Make sure that the index signal is at the correct level. For most applications it should be active low (i.e. it should be at high level during most of a turn and go low when the index mark passes the opto switch, I think it should be like this on most if not all Agilent optical encoders as you have it on your motor. This happens for a very small turning angle only and is hard to detect when turning an encoder/motor manually, so if you try to find the index signal turn the motor/encoder veeery slowly.

How do i Model the MID 7654

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