Need Help!- Can you extend the cables of an AC servo motor yourself?

[CncForMe]

Looking at getting some used drives and motors and of course there not long enough. I have noticed that the cabling for new drives is very expensive and I wonder why? I can see a need for quality flexible wire and even shielding for the encoder wires but is there something else I am missing?

[Al_The_Man]

They can be extended, it depends how you wish to do this, either set up a small intermediate box with the terminals, or inline Amp CPC connectors for example.
If you wish to keep it compact, in line splices with heat shrink tube, make sure you carry the shield over the encoder cable connection, you should not skimp on cable quality here.
The same can be done for the power conductors.
I prefer to replace the cable and just use the existing connectors, but if twist splicing and soldering with heat shrink, I apply a layer of RTV over the heat shrink splices, before it sets then cover with one Thick wall heat shrink and then heatshrink this.
Don't forget to use twisted cable for the Power conductors and also carry a ground conductor through to the motor case ground.
Al.

[CncForMe]

Alright here is another one for you... Now I have tried to do as much research on my own but I still can't quite figure out how to setup some AC drives that I found for cheap on eBay. Maybe you could steer me in the right direction. I want to use mach 3 as that is what I have been using to run my tormach mill. The drives are Mitsubishi MR-J2S 40A and I don't know how to wire them. I think from the manual they accept step and direction inputs. I have read all over that mach may not put out enough steps per minute so maybe I need more electronics.

[Al_The_Man]

Originally Posted by CncForMe I think from the manual they accept step and direction inputs. I have read all over that mach may not put out enough steps per minute so maybe I need more electronics.[/FONT][/COLOR]

If the drives accept step/dir then it should not be an issue.
I do not use mach and the only Mitsubishi drives I use are within a Mitsubishi CNC system.
Where did you get the info that the step rate would be insufficient?
Al.

[CncForMe]

The drives have something called "Position control mode" and states..

"An up to 500kpps high-speed pulse train is used to control the speed and direction of a motor and
execute precision positioning of 131072 pulses/rev resolution.
The position smoothing function provides a choice of two different modes appropriate for a machine, so
a smoother start/stop can be made in response to a sudden position command.
A torque limit is imposed on the servo amplifier by the clamp circuit to protect the power transistor in
the main circuit from overcurrent due to sudden acceleration/deceleration or overload. This torque

limit value can be changed to any value with an external analog input or the parameter.''

I am assuming this is step and direction, and fairly confident because the other modes
Speed control mode and Torque control mode require a 10 v Analog signal. I don't remember what mach puts out i thought it was something like 37,000 pules a second??? This drive seems to want 131072 pulses/rev resolution!!!! But maybe this can be changed in the drive. Still working through the manual. You know just looking a this agian help me understand the drive says as above that, if i have this right, 500,000 Pules per second can be input. But if the drive needs 131072 pulses/rev resolution it can only turn less than 5 rev's a second. So 300 rpm max that can't be right?????

[Al_The_Man]

Between Mach and the Drive, you should be able to scale the pulse/rev resolution in the drive to suit the max Mach resolution.
I will look in the manual to confirm this.
Al.

[CncForMe]

Thanks Al



Here is the link to the manual http://meau.com/Files/SH_NA_030006-J.PDF.

I can't thank you enough I am sure you can uderstand it better than I. In one of MAchMotion's servo packages they are useing MACH 3 with Mitu drives so i have more hope.

[Al_The_Man]

If you study the gearing method, particularly section 5 concerning the scaling of the input signal to rpm, CMX/CDV. It shows the formulae to calculate the parameter.
Al.

[EnvisionElec]

I just wanted to check and see if the OP found a way to interface his Mitsu drives with Mach 3 effectively. I have the same drives and I would like to know how you are able to connect the Mitsu to Mach 3 Direction control? Did the Mitsu accept the pulse train without major problems?

EDIT: Never mind on the direction control. I believe I found the answer: use PP for forward and NP for reverse. Does this sound correct? Thank you in advance.

[CncForMe]

I have not tried out my new Mitu. drive yet i need to get a breakout board. Which unit do you have? I have the MR-J2S 40 and a 400 watt motor. What are you using yours on? If you get yours hooked up can you let me know. I too need lots of help with the wiring, fairly complex imo. Hell the manual is in competition with the dictionary in size.