×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

DC master/slave commnications

DC master/slave commnications

DC master/slave commnications

(OP)
If I delay the speed reference 40ms from the master to the slave what will be the result? Will the slave droop from lack of a updated speed refrenece? Will it then try to catch up or slow down will it go into current limit? Please help with this one I need a answer if anyone can help me.
THanks

RE: DC master/slave commnications

A delay in a control loop can be modeled as multiple poles (the Taylor series of the exponential ). Generally it reduces the phase margin . E-mail me your circuit & FAX # <nbucska@pcperipherals.com>

RE: DC master/slave commnications

Suggestion: There are additional possibilities depending on the circuit design, e.g. the slave may time out and shutdown the controls depending what 40ms may impact, or the slave may or may not even notice it.

RE: DC master/slave commnications

The effect on the slave due to a delay in speed reference with respect to the master will be determined by the connection between the two. For example, do these motors drive rolls for a machine processing a sheet product (aluminum, paper, plastic)? If so, such a delay would cause a mess. I have seen droop applications where the reference (torque or speed) to the slave is reduced with respect to the master but never one where it is time delayed.  If you provide more info I am sure someone here can help.

RE: DC master/slave commnications

(OP)
I understand what you mean rhatcher I have done paper machines any web app. can be very sensitive to speed reference. This is a crane application a very large crane it runs on tracks and one side is the master the other a slave. If they are not matched near perfect then the slave could be left behind as they move along the rails. I said 40ms because that was about as fast as I could get RS232. Does this help? I hope so, I would like to thank all for your help.

RE: DC master/slave commnications

The time delay that can be provided between the master and the slave would depend on several factors:

1) The load profile that the slave and master are subjected to.
2) Whether the time delay can be absorbed by the system as a whole. It is all about doing settings and observing the final result. There may or may not be tolerences in the system to accomodate the delay.
3) If they are on rails there is still a stiff accuracy level that has to be maintained. How are the sections linked? If they have rigid links then the delay would strictly depend on the tolerences in the mechanical linkages.

As you can see the delay is a function of the process and not the otherway. For the purpose of dampening the responce of the system it can be adjusted then again with the limitations that are declared by the process.

RE: DC master/slave commnications

(OP)
It is a bridge crane so they are linked by the steel structure.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close