DC Motor Speed Control

[Thomas Sullens]

Just a thought

chip7238 I wouldn`t completely forget about current because your rpms may not be as sensitive as current. What your talking about sensing the saw mandral is good, but what about a dull saw it may turn the right speed and be tearing H*^l out of your product. You can see it in your current and the more things the plc knows the better decisions it can make. Also time how long the saws run bring on change saw light or if current has been > X so many times bring on change saw light. Don`t starve the plc for info.

 

[rsdoran]

Actually I think the prox/rpm monitor is a good way to go, just about any problems (dull blades etc) would slow the blade down. Wouldnt hurt though to use current too, the more info you give the plc the more reliable the process....as Thomas mentioned.

 

[rsdoran]

I got to thinking again....I was going to mention the use of Devicenet but after doing some research I am not sure you would want to go there.

In my research though I looked closer at DART speed DC speed controllers. They have a variety of pickups designed to work with their controllers. The Digital DC models have ALOT of features.
http://www.dartcontrols.com/products2.asp?Group=cdc-dig

This is the manual for one of them, its possible to setup serial communications too, this could allow you to monitor more of what the drive is doing. The drives themselves have a microprocessor so can handle alot of the actual work on its own..check this out:
http://www.dartcontrols.com/InternetConfig/Manuals/ASPIIMDIIRevAManual.pdf

The DL205 has serial communication capabilities but with an intelligent drive it may be possible to use a smaller plc like the little monster DL06. Let the drive do the real work and use the plc to interface to I/O and an HMI.

Grainger sells these things. I have used them for years and never realized they had models this sophisticated.

Here is a sample hookup:

 

[chip7238]

Wow guys! Thanks for the information!

I see your point about monitoring both the spindle rpm and the current as well. Although I am not too concerned about the blade getting dull before someone realizes, it never hurts to put as much info in the plc as possible.

I'll definately check those Dart controllers out - they look good on the first glance!

Thanks Again!

Chip