ENCODER/PLC INTERFACE 1

[CDPISME]

I HAVE AN APPLICATION I COULD USE SOME HELP WITH. I HAVE A VERITCAL CARRAIGE THAT TRAVELS 90 INCHES CARRYING APROX. 35 lbs. I HAVE TO STOP THE CARRAIGE AT 18 DIFFERENT POSITIONS AND TRAVEL AT 6 INCHES/SEC IN ONE DIRECTION AND TRAVEL AT 12INCHES/SEC AT THE OTHER. I NEED TO INFERFACE POSITON DATA WITH A MICRO PLC. THIS IS A STACKING OPERATION SO AT EACH POSITION THE PLC HAS TO FIRE SOME OUTPUTS. I'M LOOKING FOR A
LOW COST WAY TO CONTROL THE SPEED OF THE MOTOR AND ASLO GET POSIOTN DATA. CAN ANYONE POINT ME IN THE RIGHT DIRECTION?

 

[ctolbert]

CDPISME:

You can do this type of application with any micro/brick plc that has a HSC (high speed counter) circuit build in or a discrete circuit that can handle over 20hz (it's also scan time dependent when using a discrete input as a counter above 20hz.) The input requirement would be a quadrature incremental encoder. You could also use a dicrete input like a proximity if your application allowed for it.

http://www.automationdirect.com

http://www.keyence.com

http://www.omron.com

Another possibility would be a PLS (programmable limit switch) and a resolver.

http://www.patriotsensors.com/Programmable_Limit_Switch.html

http://www.toledotransducers.com/pls.htm

http://www.ciecocontrols.com/limits.htm

Hope this helps some,
Carl

 

[TheDOG]

CDPISME,

This sounds like a motion control/servo application. What type of motor do you have? How are you going to control the speed of the motor?
A servo system consists of a motor, an encoder on the motor shaft and an amplifier (Drive). The encoder connects directly to the drive, and the positioning error is calculated by the drive. You can get high torque and high speed combinations.
The drive will usually have a buffered encoder connection for use with any external control. It will also have I/O, so connection to a PLC is usually not required.
Price of a motion control system is proportional to:
Accuracy required
Speed required
Tourque required
Bandwith (or response time)

Good Luck!!!

 

[bogdal]

You can visit the site of Siemens :

http://www4.ad.siemens.de/csinfo/li...csallprompt&SearchType=9000&func=cslib.csinfo

Depending on the motion transducers You have, you can choose the right interface module, to control the position and the speed. You can find also the right operator panel to configure and to watch the entire process.
What kind of motors do You use? A step-by-step one it would be very easy to control

 

[kinplc]

there are a special sistem from control techniques,is a servo that you can programer, in a basic lenguaje, very easy and is very cheaper than other systems, contact wit control techniques, for me is the easier and cheaper system.

 

[MGT]

I don't know how much HP you need but, you may be able to use a stepper motor and drive to do this application. The programming is usually straight forward. The pricing will be less than a servo, you can control speed accuratly, position is no problem. Good luck.

 

[newsarang]

From the info you have given,the 35lbs wt. and the speed,I feel that you can use a stepper motor and a drive with encoder feedback.You can get a good accuracy and the stoppages can be programmed or you can fix sensors(proximity)at each stopping location.This is a very low cost solution as compared to servo.Hope this info is okay and help you.All the best!

 

[JayAnthony]

The Omron CPM2A or CPM2C can provide both the quadrature input and the pulse output to control either stepper or pulse-driven servo.

http://oeiweb.omron.com/oei/

 

[pekan]

I am in the process of completing a similar project.
My motor is 20 HP DC. It needs to drop a part @ 1700rpm for 210", then change speeds to 500rpm and drop 36" all in 7 seconds.
We are using an AB1397 DC drive, to control speed/direction. A 180PPR pulse encoder hooked up to a 6 setpoint batch counter. The batch counter sends 24VDCinputs to a SLC5/04. The slc contols the DC drive by contact closure. No costly analog i/o needed.
My solution although not sophisticated, is cost efective, easy to confugure, and reliable.
Red Loin Industries makes good inexpensive Batch counters.
I hope this is some help!
Good luck
John McCann

 

[djs]

Hello;
Try using a PLC with a high speed counter/stepper motor controller. Allen-Bradley SLC has one for example. Also Koyo (automation direct has one). The HS card outputs to a stepper motor controller which moves your table.