Help please !!! Servo configuration with stepconf.

Does it have a setup procedure in the manual? You will have to tune the drives to use them.

I have 2 5i25 setups one stepper and one servo. The installation is quite neat with one round cable between the PC and the daughter card. I also have one 5i20 servo setup. For me unless I needed some feature on the 5i20 any new conversions would use the 5i25. You need to study each then make up your mind.

John

ishman wrote:

My drive model is SA3L04C
www.bonmet.com/productshow_eng.asp?id=1506

Actually, contrary to what other have said, it seems that that drive _will_ work with step/dir signals.

As an aside, that looks like a really good driver for LinuxCNC use, and the mains-voltage input is a huge advantage compared to many. The price (£245) is competitive too.

I would guess that to calculate the steps/rev you need to choose the encoder resolution of your motor, though the "electronic gearing" of the drive might change that.

If the motor encoders are high resolution then you will probably need to use the "elecronic gearing" as a standard parport will struggle to output pulses fast enough to give you adequate motor speed.

So, in Stepconf you can probably pretend that it is a 1000 steps-per-rev stepper motor, then see how far off your physical scaling is, and adjust it. (by which I mean program a 1" of 25mm move, measure how big it really is, and then adjust the steps-per-rev to suit.

Having said that, step-dir mode with the position control inside the drive is not the preferred way to control machines under linuxCNC. We prefer to use analogue voltage control and move the PID loop inside the control PC where it is easy to watch what is happening and tune the PID.

If you are using that style of drive and the sorts of motors that suit it, I suspect that you have quite a large and serious machine, and in that case you will probably find yourself running out of IO lines on just a parport, and the 7i77 mentioned earlier will be a good upgrade.

BigJohnT wrote:

If you run out of I/O on the 7i77 then you can get a second card to expand your I/O. I'm not sure which card that is

You can connect a single SmartSerial card to the 7i77 to add up to 48 lines of IO (and they can be 2.5A / 48V rated IO with the 7i64 card)
Compatible cards are 7i64, 7i66, 7i69, 7i70, 7i71 or the 7i74 remote pendant interface.
However, the second header on the 5i25 allows you to also add a 7i74, and then you can add up to 8 more of those cards above.
So you could have another 432 IO lines additional to the ones on the 7i77 board. Probably enough for most purposes.

LinuxCNC includes a software PLC (Classic Ladder) and so you shouldn't need any additional external PLC hardware.

That's what I was referring to the internal set up and tuning of the drive itself. Using step and direction once the drive is tuned internally to the motor/load/friction it should move on command with step and direction inputs. You mention that it does not sound right when you try and use step and direction and this might be a result of the internal settings of the drive not being correct.

John

BigJohnT wrote:

You mention that it does not sound right when you try and use step and direction

It is also possible that the drive can't auto-tune to a bare motor. This is not at all unusual, as a bare motor is far too responsive compared to a typical servo loop. It might well be perfectly acceptable when mounted on the machine.

You will have to figure out how to set up and configure the drive software before you can use any control software to run the drive.

I don't have a clue what you mean by program Classicladder twice??? If you can program ladder you won't have a problem programming Classicladder. Classicladder also has the benefit of directly interacting with HAL pins something and external PLC can not do as it can only see physical outputs and control physical inputs. Granted the UI for Classicladder is a bit poor but in a few minutes an experienced PLC progammer would be off and running. The biggest hurdle for most folks in Classcladder is ladder logic itself which is a bit foreign to most folks who know a little about programming C or basic or whatever. Just try and explain to someone who does not know ladder that if you have the same output in two rungs the last output wins!

John

ishman wrote:

I meant external motion control programming like job placement and removal, vice clamping, direction swapping, tool change etc. Because my machine is built for heavy jobs. If we need some extra motion control then every independent motor needs an axis and AFAIK linuxcnc can only handle 9axis at this moment. .

True, though for simple non-coordinated moves (i.e. where actuators don't need to work together to move the controlled point) it is possible to use analogue outputs from G-code through a HAL Limit3 block into a PID or stepgen and from there to the drive/motor.
The are G-codes to pause until a digital input is seen, so the code can pause until the actuator gets to the controlled position.

(This is only one way to do it, there are others)