ENCODER /PLC INTERFACE

[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?

 

[tinker]

You need to specify a few things to be able to better define your solution.
Will the 18 positions be fixed for the life of the machine?
Are the positions incremental or random?
Are the positions on common a repeat?
What do you consider low cost?
What is the expected positioning accuracy that is required?
As the machine ages some methods will become less accurate, what would be an acceptably rebuild time frame?
How much work do you plan on putting into the project?(electrical, mechanical and programming) Building it yourself type will usually take more of your time and skills but most of the time will save $$.
Can you use a PC rather than a PLC?
Is this a new system or a retro fit?
Do you have the drive system already?
By the way all caps is considered to be SHOUTING. At first it is awkward to use the shift key but after a will it is easy!

Blessings to you in Christ
Tinker

 

[Tom001]

If you can get hold of the PLC system from and old Gosewehr cartesian robot (as these are now relatively cheap) the PLC will provide onboard digial inputs/outputs and is expandable but you could strip off the servo motor and encoder, this will be already interfaced and can (depending on the mechanical side of things) give an accuracy of +/- 0.1mm approx with speeds and accelerations programmable.

To find these check the plastics and rubber weekly website for secondhand suppliers

I hope this of use to you

 

[Skidog]

Have you considered using an AB PLC, maybe an SLC500 series 5/04 with a AB 1746-HSCE High Speed Counter Card for the encoder inputs? I used this once to control 3 axis on a material handling crane with great success. (It's not necessary to use the 'Z' pulse) The motor is driven by a Mitsubishi Freqol series variable speed AC drive.

I have plans to upgrade a similar crane control system using a Banner laser and an AB analog input card (0-10v)in the coming weeks. If your interested I can post my results here with a sample program and interconnect drawing.

In case you wondering I'm a technician who does everything from engineering to installation. Do I have a great job or what?