Dynomotion

Group: DynoMotion Message: 5715 From: craig.trimble@rocketmail.com Date: 9/27/2012
Subject: Cintimatic Retrofit
Hi

We are attempting to reto fit a Cincinnati Cintimatic 5VC-750 Vertical Spindle Mill, with a 24 tool magazine, with the eventual aim of running both the tool changer and 4 axis through Mach 3 on a K-Flop and Kanalog.

The Servo amplifiers are Advanced Motion Controls PWM max current rating of 30 amps (15 continuous) driving Siemens DC servo motors with tacho generator, running in velocity mode, and a Fanuc Spindle and AC Spindle Drive controller.

Running heidenhain LS403 20 micron pitch 50 line per mm glass scales, with quadrature output being fed into a exe box, running a 2 channel square wave output with 1/2 micron pitch. The exe outputs are running into the kanalog A0+ andB0+.

We were getting a lot of noise when we scoped the output of the exe box, but seem to have cured that by screening the wires from the reader head to the exe box.

At this stage we are concentration on one axis at a time, and are driving the x-axis using the Kmotion program.

We can get the table to hold position and drive using the move command in the step response menu, and the move profile graph looks very good. The problem we have is that we are achieving lost motion when we return to the zero point. The position display shows us returning to the start point, however the dial indicator on the table shows a random small position loss (up to 50 microns). This position loss does not seem to be scaled with the size of the move.

Have you experienced lost motion like this before?
Could the resolution be too high for this application?
Is the fact we're only inputing a single A and B to the Kanalog likely to be part of this problem?
Any other possible suggestions?


Also could you provide me with the recommended connections for the opto inputs and fet outputs.

Thanks in advance

Craig
Group: DynoMotion Message: 5716 From: Tom Kerekes Date: 9/27/2012
Subject: Re: Cintimatic Retrofit
Hi Craig,

Thanks for the thorough description of what you are doing.  Yes the problem is most certainly that you are only driving one side of the differential Kanalog encoder inputs.  This is a common problem that Users often make and I'm always surprised it works at all.  A differential input needs to see a + and - differential voltage across both inputs to work properly.  If one side is floating (or ground) then this won't be the case.  I don't know what the "exe box" is you are referring to but I assume it converts the sine/cosine scale signals to digital quadrature outputs.  I'm surprised it doesn't have differential outputs.   If it really does not have differential outputs then there are low cost converter modules available to take a single ended signal and convert it to a differential signal.  USDigital (and I think Digikey) sell such converters.  See:

http://www.usdigital.com/products/interfaces/encoder/cable-drivers/EA

Another option is to bypass Kanalog's differential inputs and connect the single ended encoder signals directly to KFLOPs single ended inputs.  You can do this by unplugging KFLOP JP5.  This option would be more noise sensitive and you would need good shielding and some external termination resistance near KFLOP to get reliable performance.

Regarding the Kanalog opto inputs it depends on what you are interfacing to.  But basically 5-24V needs to be applied across the + and - inputs to be activated.  You are basically powering an LED through an on-board resistance.

The FET outputs can sink a signal up to 24V @ 1A to ground.  If they are driving a mechanical relay coil or solenoid the driven coil must have a fast reverse diode across it to avoid a large negative voltage spike (spark) when the coil turns off.  A good method to get optical isolation is to have them drive solid state relays.

HTH
TK