SIMPLE servo motion control

[LURBY 1]

I would like to create a simple motion control using AB products. I currently use an Ultra 3000 drive to control a MPL... servo motor. I put the drive in analog mode, give it a 0-10v signal and off it goes. I take the signal away (when I hit a limit switch) and the motor stops. Pretty basic... I would like to add position to the equation. This means some type of "motion controller" but Allen Bradley doesn't seem to offer anything called motion controller. I am currently using a PLC to control my I/O. It is a ML 1000. I have been told by my AB distributor that if I wanted to control the motion I would need to step into the CompactLogix world. That means RS5000 and a whole other ball game that I don't think I am ready for. I am pretty comfortable in the RS500/MicroLogix world and don't want to leave if I don't have to. I have a slide controlled by a ball screw/servo motor. I would like to be able to give the drive a position (say 12" away from home) and a speed (say 2 inches per minute). I could use a touch pad for the data entry. This info would go into the PLC. Calculations would be made inside the PLC that would convert these units into something recognizable by the servo. (I would need to know the pitch of the screw, RPM of the motor, etc.). The PLC would covert this to an analog signal and send it to the Ultra??? I know that they have come out with a number of new ML controllers. Are there any of them that will do something like this? Has anyone done it? Is it worth the hassle or should I bite the RS5000 bullet?!? Is there another way? Thanks for your input in advance! Chuck

[JRoss 84]

You can do simple servo positioning control with a Micrologix 1200, 1400, or 1500. Check out the PTO instruction in the help files of RSLogix 500. You'll probably want to talk to your AB rep and ask for some sample programs to get you started. Positioning control is a different animal than speed control. You'll likely be able to stick with the same servo, just change the parameters to take a pulse train input for position control.

[bikerdude 0]

Hi, I have seen several servo systems (linear motion) that are supervised by a SLC500. I am not familiar with the AB Ultra 3000, units but the others models I am familiar with use preset "indexes" as a method of getting precise position done quickly & repeatedly. The servo driver module will need a connection to a encoder or resolver and a "Home" proxy. After the homing process is complete the PLC is able to send commands (digital I/O) to the servo control module. While the servo is executing a move or index procedure it will keep sending a "Busy" signal back to the PLC. When the motion index is complete, the servo controller will discontinue the busy & send a index complete signal. Of course there need to be over travel limits to stop the servo from destroying the mechanical devices attached. Most of the time the linear motion is back & forth repeating in a fast and accurate placement of something. Most of the programming is done in the servo module. The SLC just monitors the rest of the process & tells the servo when to run to a certain position. Once an "Index" is programmed in the servo controller I don't think it can be modified by user input, I don't think so but I could be wrong. Just an option to look at. BD