I have a machine with an old 1990s CT FNC4 controller that has had its memory card removed. Apart from that the machine is fantastic, beautifully made with linear rails on a granite base, servo motors encoders, NSK spindle with air bearings and a cooler to keep the spindle at constant temperature. There is a full controller cabinet with the FNC4, the 3 servo drives a PSU and operators panel with MPG.
Assuming its impossible to get the FNC4 working what controller would anyone suggest that can handle servos and encoders?
I would be happy to commission someone to help me convert it in exchange for one of my working CNC machines.
It seems, you need an analogue control Unit like the CSMIO IP/A or you can change the servodrives to new parts which can controlled via Step/dir.
The last possibility will be cheaper, because you need only a bob, if you have not many IOs. But with many IOs its better you buy a dedicated
motion card, which can handle it.
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This won't be a simple or cheap conversion. Most whats on front of the control console probably won't be usable as it will be bespoke to the FNC4 controller.
Like been mentioned the Servo drives are probably Analog controlled not Step/Direction which straight away makes it more expensive because there are not many Analog controllers available. They may even need higher Logic level voltages than usual to work ie: 12v or 15v compared to usual 5v most controllers provide(Cslabs units included)
Chances are the Servo motors are DC motors and most likely brushed not brushless and will/may have tacho. Changing the Servodrives is an option but won't be any cheaper because you'll still require Motion controller with lots of I/O and you'll lose some of the advantages Analog and Encoders give regards closing the loop back to the controller compared to Step/Dit that only close it between motor and drive.
Then you have the hassle of PID tuning the new Drives to Old motors along with tuning drives to controller rather than just tuning the Controller to the drives. Not always a simple affair and very important if motors are to perform correctly.
So what I'm saying is that do some research before diving into this and don't just let any old muppet take it on because it's very easy to get wrong costing lot of money and ruining a very nice machine.
i saw the CSMIO and was not sure which model. I assume you suggest that model as my older servos will be ananloge.
RE I/O there are limit switches, sensing air pressure for the spindle, power for the cooler. At present the spindle is connected to an extra axis, i assume to receive an analogue signal for the inverter driving the spindle. Can the CSMIO accept encoder input?
That depends what you want to do.
If you want to reuse the existing drives, you need the IP/A, if you want to change it for modern drives you can buy the IP/M. I don't know the prices,
but you need 100quid for one drive.
The new drives can be controlled with step/dir. But you must connect the encoder lines directly to the drives. They need to have an differrential (maybe single-ended is enough) TTL output. If you have another signal, then maybe you can change it, with special electronics. Or you must change it with an encoder from HP/avago.
Your drives are capable of a bit more then 60V and 3Amps continuous/ 6 Amps Peak for 1 second. So you need a brushed DC/Motor drive with not less then these amounts.
The only drives I found for my machine are Leadshine DCS810 or american Geckos, which are doubled as expensive.
Last edited by uli12us; 02-01-2016 at 03:57 PM.
It will be cheaper to change the controller to the IP-A version, changing the motors and drivers will cost more than the new controller and will also need mechanical changes to the motor mounting flanges. After this you would then need to add a motion controller, because a standard breakout board will not handle the 24V I/O let alone the amount of I/O you will need.
This conversion will take time and this will cost more than the parts if you are paying someone else to retrofit it. Do you have the documentation on the machine? like the wiring or at least the installation manual for the controller and drivers?
before you go any further, you need to know if the existing motors and drivers are actually working? and you need to check if the encoders are incremental or absolute. If they are dodgy or absolute encoders, then changing the motors and drivers may be the way forward, but also changing the controller to an IP-S or M, but i would favour the S version.
I could do it, but i have about four other machines that i need to do first.
You don't need to change the motors, changing the drivers is enough.
60V and 3/6Amps isn't really expensive.
The Gecko 320X or leadshine DCS810 each with 80V 20Apeak are more than capable for this.
But the encoder of the motors must have a TTL output, single ended is enough.
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