Messages

3391

General Mach Discussion / Re: To smoothstepper or not?

« on: December 07, 2018, 09:34:11 PM »

Hi Gerry,
I always had a pretty good run out of the parallel port and had a very good 'flat line' DriverTest.exe response. As such I did not expect to see
a dramatic improvement when I went to a SmoothStepper.

What I got impressed me, I had been running my 5 phase Vexta steppers at 1800 rpm during G0's without good reliability under the parallel port.
When I switched to the ESS I was able to increase the G0 speed to 2400 rpm and run marginally cooler. Also the sound the motors make it not as harsh.
I ascribed, maybe mistakenly, that the 2-4us of jitter of the parallel port was sufficient to induce a rather harsher noise than the same motor under the ESS.

The only time I got into any bother with the parallel port is if I had some CPU intensive task running in the background or a large file where the redraws would
either stop, stall or stutter Mach. I've found the ESS to be somewhat more forgiving in that regard.

The increased range of highly suitable PC's and OS's that come from using a good external motion controller lead me to recommend such a controller alone.
The perceived, real or otherwise, increase in performance is a bonus.

Craig

3392

Mach4 General Discussion / Re: Hybrid Stepper Setup in M4

« on: December 07, 2018, 09:16:12 PM »

Hi jm2020,
on page 63 of the manual there is a list of the various modes of operation making use of the highspeed RJ45 connection.
All of them rely on communication with a PC or PLC on a shared bus arrangement. Nowhere does it mention using the RJ45
connector as step/direction input. I was of the opinion that's what you were doing. Am I mistaken?

If I am mistaken and Steve is correct then you can only signal the steppers with the pins available in the P2 connector which are limited to
5kHz which is too damn slow to be much good.

Craig

3393

Mach4 General Discussion / Re: Hybrid Stepper Setup in M4

« on: December 07, 2018, 08:59:15 PM »

Hi Steve,
OP has used the Lexium tuning software at 256 microsteps per full step for signal rates in excess of 1 MHz using the Ethernet connector.

The spec you read on page 22 relates to connector P2, not the Ethernet connector (RJ45) which is described on page 23:

RJ45 Standard RJ45 connector for CAT5/6 cabling capable of 10/100 network
speeds. TCP/IP settings are modified using the TCP/IP Configuration
Utility. See the Lexium MDrive Software Suite Manual.

If OP is trying to use the opto-coupled inputs in the P2 connector then it is no wonder that it wont perform as he expects.
Having said that a cursory scan of the manual doesn't suggest that you can signal step/direction signals into the RJ45 port, despite
me having formed the impression that OP has done exactly that.

Craig

3394

General Mach Discussion / Re: To smoothstepper or not?

« on: December 07, 2018, 08:39:12 PM »

Hi,

Did you notice any improvement in the quality of the cuts you were making

No, not really, I mean a parallel port would have to screw up pretty badly before it deviated from the toolpath or jittered
enough to affect the cut quality. Of course the parallel port did from time to tine screw just exactly that badly.

The SmoothStepper is better in that regard....it takes a lot more hamfisted interference by me before it screws up.

I've always commented of the money spent on improving my machine the best value were good quality roller plunger microswitches
for my home switches and the next best item is my ESS.

Craig

3395

Mach4 General Discussion / Re: Hybrid Stepper Setup in M4

« on: December 07, 2018, 05:11:04 PM »

Hi,
maybe:

https://www.ebay.com/itm/TTL-To-RS485-Adapter-485-Serial-Port-UART-Level-Converter-Module-3-3V-5V-S2-O2G2/282779620056?epid=2213336341&hash=item41d6fa92d8:g:7iwAAOSwH2VaOnvl:rk:11:pf:0

Craig

3396

Mach4 General Discussion / Re: Hybrid Stepper Setup in M4

« on: December 07, 2018, 04:47:32 PM »

Hi,
increasingly I'm thinking that there must be a mismatch in signaling causing the drift you have described.

If for instance Mach4 was faulty in that it produced 4000 pulse one way nut only produces 3996 pulse when going the other way
than ALL mach4 users would be affected. Do you not think that would be trumpeted loud and clear!

Likewise if its a fault of the 57CNC then ALL those other users have not encountered the same problem, I suspect extremely unlikely.

Given that the Leixum setup app is performing perfectly and as expected then you know that the stepper itself is capable.

That really only leaves the signaling between the two.

I have attached the representative output circuit of the digital output of the 57CNC. It is not clear whether the output you are using has the resistor in circuit
or not but the current output specs suggest it is not trivial, 8mA vs 50mA. The next thing to note is that the output pin is driven by the MCU which
is almost certain to be totem pole TTL output. This style of output is very common and woulds drive the input opto-coupler of many stepper drives or servo drives.
Note also that such opto-coupled inputs are speed restricted to about 100kHz. The 57CNC output is speed limited to 125kHz per manufacturers spec.
Given the majority of the devices which PoKeys might reasonably expect their controller to signal they can be satisfied that their controller is very capable.

If you scan the specs of most servo drives you will see that most tolerate single ended inputs of up to 100kHz but thereafter require differential signaling
up to the common limit of 500kHz.

Then you come along with a differentially signaled device. Lexium can be forgiven in that in order to signal their stepper  requires signals in excess of
1 MHz then a good quality differential signaling scheme is mandatory. Ethernet is a good quality differential signaling scheme that is widely supported
with low cost components and chip sets and they have taken advantage of that.

I think you have to try either in IC such as I have linked to (the second and correct link! Ahem!) or use some of the little RS485 driver boards that abound
on EBay and similar.

3397

General Mach Discussion / Re: To smoothstepper or not?

« on: December 07, 2018, 03:50:37 PM »

Hi,
just as an aside in most circumstances increasing the G0 maximum velocity does not improve cycle times a great deal.
Most CNC jobs do not spend a great deal of time operating at maximum G0 speeds but are accelerating up to that speed
but then have to start slowing down again without ever having reached maximum speed.

Increasing maximum acceleration is very much more relevant to cycle time under those circumstances and acceleration
comes back to motor torque. When I fitted and set up my ESS (Ethernet SmoothStepper) I increased the acceleration in
addition to the max speed. I can't remember by how much. I do remember increasing it (without losing steps) so much that
my machine was rocking around so much that I had to tie it to the wall! So I backed off quite a bit. So my machine is capable
of quite a bit more acceleration than I'm comfortable with in practice. I'm sorry I don't have or recall any numbers or even indeed
whether it was the ESS that allowed the increase, it may be that the machine was capable of considerably higher acceleration
when I was still using the parallel port as well.

Craig

3398

General Mach Discussion / Re: To smoothstepper or not?

« on: December 07, 2018, 02:30:15 PM »

Hi,
when I went to an Ethernet SmoothStepper, a genuine Warp9 TD unit, not some Chinese knock off.....don't worry there are plenty out there,
I was able up increase my G0 traverse speed by 33% and the motors run a little cooler and sound 'smoother'.

Craig

3399

Mach4 General Discussion / Re: Setting Motor Counts Per Unit in macro

« on: December 07, 2018, 01:25:53 PM »

Hi,
there is an API for that, but I'm not sure that it was intended for use on the fly, that is to say I thought it was for use in plugins
where a parameter, in this case 'steps per unit', were set for a device and then left alone.

LUA Syntax:
rc = mc.mcMotorSetCountsPerUnit(
      number mInst,
      number motorId,
      number counts)

Description:
Set the counts per native machine setup units.

Craig

3400

General Mach Discussion / Re: Retrieving position after an e-stop or other position loss

« on: December 07, 2018, 01:17:23 PM »

Hi,

What methods does mach software have for updating position based on an external reference?

That might be a little trickier. It has been some while since I used Mach3 so I can't be 100% that the situation is the same as it is
in Mach4 but to the best of my knowledge it is the case.

The only way to change machine coordinates in Mach is to either move the machine OR reference it.

You might have thought that:

LUA Syntax:
rc = mc.mcAxisSetMachinePos(
      number mInst,
      number axis,
      number val)

From the API would set the machine position, ie the machine coordinates, but I have tried using it and failed. This is from the same API note:

Parameters: Parameter Description
mInst         The controller instance.
axis            The axis ID.
val             The desired axis position to apply a fixture offset.

So when I did try it was the fixture offset that changed not the machine coordinates at all.

If there is another way of doing it I don't know what it is , maybe someone else can chime in.

Craig