• Thread starter Marian Stolarski
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Marian Stolarski

Does anyone have any experience working with the UNIDRIVE (with modul UD76) variable speed drive for induction motors?. I'm starting an application with this drive to use it in the lifting mechanism. Drive will be control by PLC MODICON QUANTUM via MODBUS PLUS network. Is it
possible to control a drive from two sources at the same time, e.g. from PLC via network and from drive terminal? I need also tech info about motor encoder sizing for this drive.

Forgive me language, please.

Marian Stolarski
Hutnicza 1, 62-510 KONIN,POLAND

Leighton Toews

We work with these drives a little. It is possible to do what you suggest, control via network as well as via drive keypad, be aware though that one could over-ride the other. As to the technical specs of the drive, I suggest you contact Control Techniques, the manufacturer, regarding that.

Leighton Toews
Process Control
Del-Tech Industries

We have used the UD-76 module for connection of UniDrive using Modbus+ to a Modicon PLC. First recommendation is to make sure you map your
UD76 memory to contiguous memory locations so that communications with the PLC are done in convenient blocks rather than in hunt and peck mode. (i.e. write a script in the UD-76 that gathers the information of interest from all over the drive and copy it into contiguous registers
of user memory so that it can be picked up in a block. Also writes from the PLC should be done to a contiguous block of user memory and then
copied to the appropriate control registers in the drive. This is not necessary, but does speed the communications dramatically and make
programming on the PLC side much simpler.

The drive works well as a Modbus slave and power cycles do not adversely affect the network.

As far as lifting mechanism . . . if drivetrain is not self locking, you should coordinate a brake and also some code that checks to see if the
drive is putting out current prior to releasing the brake (torque proving). This can be done with local drive I/O or with PLC I/O.

Running the drive from the keypad AND the modbus interface? You will need to write code that reads local drive I/O and set up a switch for
network or keypad operation. This is easily accomplished . . . however, you must keep in mind that you don't want any of the modes of operation to allow an untrained operator to drop the load.

Best Regards,

Ken Brown
Applied Motion Systems, Inc.

krishnaiyengar sudershan

i have worked little bit on this drive..... may be different model. But they have a configuration known as brake mode..... through this you can achieve the required functionality. As mentioned below, you should have some current prior to release the brake, or else the load may drop...

thanks and all the best


krishnaiyengar sudershan

i too agree with that. i myself seen that the terminal pad overriding the commands driven by the PLC. This has led to falling of one of the car body during one of my project. Also you have to be pretty sure of working procedure for lifting mechanism. As far i know it is to be programmed in brake mode. it is better to get more information from the Control technique
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