Hi,
I think that if your servo has a 17 bit encoder then it will be absolute and if memory serves it has a resolution of 131,072 counts per rev.
Lets work backwards and say that for simplicities sake you wish to keep the pulse rate to 100kHz. I imagine you'll still wish your servos to achieve max speed,
ie 50 rev/sec. Therefore the resolution is limited to:
100,000 / 50 =2000 counts per rev.
The electronic gear ratio is 131072/2000= 65.536 If you read the manual the gear ratio can be selected with two numbers, a numerator and a denominator.
Both numerator and denominator have to be integer and less than 65536. The exact ratio could be achieved by selecting numerator as 65536 and denominator
as 1000.
Just as a matter of interest with a 2:1 reduction and your servos having 2000 count per rev resolution your linear resolution would be:
5 (mm/rev) / (2 (gear reduction) * 2000 (servo count per rev)) = 1.25um, pretty damn good. Your Steps Per, that you would put in the motor tuning
would be 800 step/mm. If the servos reach their max speed the axis velocity in the motor tuning page would be 7500 mm/min, there again that's great
speed for a hobbyist machine.
I imagine you'll have a breakout board between the UC300 and the servo drive. Unless you bought an absolute dog any breakout board should do 100kHz
in a canter. ger21's recommendation, a UB1 sounds good.
There should be no extra circuitry required between the BoB and the drive. Probably a good idea to use a shielded cable and don't make the cable
any longer than it need be. Microphone cable would be a good idea, its beautifully flexible and shielded to preserve low level signals, two wires plus the shield.
That would cover your Step and Direction signals.
As I posted earlier you will need some extra wires, they will not be high speed signalling wires. One will be a Mach output from the UC300/BoB to the drive
to enable it. There will be one wire from the drive to a digital input on your BoB/UC300 to Mach to flag a fault. The last wire will be an output from Mach
to rest the fault condition. Note this last wire could probably go to the fault reset input of both servo drives.
You'll need to program your drive. I see in the manual that Delta produce software to allow you to easily program you drive. Do you have it? My Allen Bradley
servo can only be programmed this way, and its very very good. It has a database of all the servo motor models with all the limiting values, physical, thermal
and electrical characteristics and makes choosing and defining parameters for your application easy. Delta drives can also be programmed with the digital
keypad, tedious but doable.
The essential parameters to set are that you wish to use step/direction position control. You need to set the electronic gearing numbers. There will also be the
limiting values, things like max speed, max current, overload duration and others. Hopefully Delta's setup software will provide all of those.
You will need to assign the digital inputs, your enable and fault reset signals and one digital output, drive fault signal.
Most servo drives, I haven't read the manual closely enough yet, allow you to hook limit switches direct to the drive. As you know it is common in Mach to hook
limit switches to your BoB/UC300 to signal Mach and Mach shuts down as a result of a over limit excursion. With a servo drive you can, within limits, program
what you want to happen. The limit switches would be hooked direct to the drive and would stop the servo from exceeding the limit and would prevent any jogging
which would take the axis further out of bounds. It will if you wish signal Mach on an output of your designation of the condition. It could trigger some automatic
response like rehoming as well. I've not heard any argument that suggests that hooking limits to the drive offers any compelling advantage over hooking the limits
to Mach. As I'm using my servo as a spindle I've not had to worry about it. My suggestion would be to hook your limits to Mach in the normal way to start with.
If a reason comes up to change that strategy do it then. Keeping it simple to start with is probably the way to go.
You may have noticed in the manual that you can directly jog a drive by using two inputs per your designation and those inputs could be hooked to physical buttons
via your UC300/BoB. Likewise you can program a number of positions that can be selected by reading a number of digital inputs of your designation. In short the
servo drive has many more options than is required for your lathe but could be a great deal of use in huge printing press for instance which could have hundreds
of servos for any number of tasks. That those options exist does not mean you have to use them but could be useful to you at a future time.
Craig