How to read/confirm 7344 settings saved by MAX?

[rws]

I am using LW/CVI software, MAX 3.1, MID-7654 Amplifier and PCI-7344 card on 3 axis servo system. The system periodically behaves weird and I wish to confirm the settings are correctly being saved and re-initialized. How do you decode the XML file generated through Save Settings? 

I have saved the same settings to two different files and examined the files and they are very different with many line differences even though the exact same settings were saved - first to file1.xml then to file2.xml.

Thanks for suggestions/information. 

[Kristen_K.]

Hi rws,

What type of strange behavior are you seeing?  Is there something in particular that points you to the initialization settings?  Are you seeing the behavior when importing the same XML file?

Kristen H.

[rws]

Hi Kristen -

I periodically see odd behaviour and wanted to confirm the MAX settings were being correctly written to the 7344 card. One thing which is happening on one channel is that the motor always moves in the negative direction at start of move .... whether the target is positive or negative. At one point I experimented with the STICTION settings and I suspect that may not be cleared even though I have turned it off in the MAX Settings and then written the settings and re-initialized. 

Also I have tried writing settings, changing a few things in the max display, then reading settings and found that the changed settings did no adjust. 

Initially I thought there should be a way to 'read' the xml file. That is, I assume there is some way to decode it so that the various identities are translated into property name and value. That is my question. 

Thanks

Rick

[Kristen_K.]

Hi Rick,

Another customer saw similar behavior using the 7344 and MID-7654 with servo motors.  The motor always moves in the negative direction no matter whether the target position is positive or negative, in absolute position mode.  They disconnected the encoder, set the P gain to 100, set the target position so something less that the following error, and tried running the motor.  The motor went in opposite directions for positive and negative target positions.  Then they went through the tuning process listed in this KnowledgeBase: A Simple Method for Servo Tuning. 

Here are a couple other resources about servo tuning.  

Understanding Servo Tune

KB: Unable to Tune a Servo Motor

Kristen H.

[rws]

Hi again -

It is unclear how the customer with the negative travel problem resolved it. I have gone through the Tuning process many times.  Is there any more information on how that customer overcame the problem? Is that mentioned in the NI Discussion Forum somewhere??

But that gets back to my original question:  How do you read and confirm the settings which are in the XML file? 

Thanks

Rick

[Kristen_K.]

Hi Rick,

The information about the other customer was taken from the notes another Applications Engineer took after speaking to the customer on the phone.  Unfortunately, that is all the information I have.  

As far as the XML file goes, since Measurement & Automation Explorer (MAX) is the only program to read an write it, the file will not be altered between instances of loading the same file.  The XML file is not designed to be manually parsed through.  Loading the file into Measurement & Automation Explorer (MAX) and checking what changes after loading another XML file will be just as effective and probably faster than parsing through the XML file.  

Is there any more information you can provide about your troubleshooting? 

Kristen H.