Greenie problems configuring 6i25 with 7i77, using Granite Devices VSD-E drives

While disconnecting the motor can be a good idea for early testing. It is far from necessary. You can and should get your encoder scaling and direction correct first before ever enabling a drive. Then set the following error limits to a reasonable safe number like 1. Large enough to see movement and see what is happening, but small enough to prevent disaster. Start tuning in the center of travel to give you the most room possible in both directions.

It's not always as bad as it sounds. Good luck.

By using the open loop test, you should be able to minimize the runaway problem.
Run the test and make sure when running in the positive direction (pressing the positive button), the axis moves in the proper positive direction.
Take care that depending on the machine this won't be obvious, movement is based on TOOL movement so if the AXIS moves the the direction is opposite - look at that diagram in pncconf - it shows the idea.
If that test proves right then check to see that the encoder counts in the positive direction when moving in the positive direction.
Do that test with all the axes and fix any inconsistence. The nice thing here is you can do the test with a very low speed.
But make sure you have a way to kill the servo power instantly - just in case

Chris M

I did, in fact, find the open loop test of pncconf to be very useful in determining that I had to invert both the motor and encoders for all of my axis. So, I feel good about that.

I am not too sure what I should do next, but my sense is that it is to determine the PID of the different axis. I need to find where the tuning is on that, but I'm sure it is in the manual. Andy pointed to a document but it was short on specifics of how one starts the process. It merely said something like, "start the tuning process" and not, "the tuning process can be initiated by navigating to the xyz button within the zyx application." There was a certain amount of inference that one knew the different components of LinuxCNC which, right now, I do not.... But the onus is on me to find my way around that.

Anyhow, my plan is to tune the axis and then work on the homing process. Working at the machine is somewhat tedious so I think I need to also load up my laptop with LinuxCNC so that I can research/learn in a more comfortable setting.

How you open the calibration window will depend on the GUI you've chosen for Linuxcnc. If you're using Axis, start Linuxcnc, pull down the Machine menu, then click Calibrate. This will open a window where you can adjust the PID settings for each axis. Then open Hal Scope, from the same Machine menu click Hal Scope. You will have to configure some settings for Hal Scope the first time you use it.

So, I've been going over the HAL commands and such. I don't see how one sets Mode 3. Hints?
[edit: I think I found the answer to this one... change the sserial_port_0=000xxx to sserial_port_0=30000000]

I'm also grappling a little with whether or not I need a PLC. I think I will, but for simple tie-ins of homing sequences, is it possible to do it without a PLC? I am using the Boss machine template as a guiding principle. Unfortunately, it uses boss_plc which I haven't located yet. I'm making good progress with my HAL configuration but falling a little short right now on the PLC side of things.

Alan

Each of the digits in sserial_port_0=000xxx represents one of the serial ports in the system, the x represents a smart serial port that is disabled so that it's pins are avalible to use as gpio. The 7i77 uses 3 smart serial ports one is the isolated field io, one is servo analog outs, and one is the smart serial expansion port. (I'm not quite sure which one is which). But you need to change the 0 for the one for the isolated field io to a 3. I think it is the 1st one so "sserial_port_0=300xxx" should be right (but it could be the 2nd or 3rd).

Perfect, thank you Todd...

It is interesting. I've never gotten a good feeling for how many people are using the Mesa 7i77 or, for that matter, LinuxCNC. Some of the information out there is surprising bleak when attempting self-help through Google searching. I found only a few hits on getting the Mesa configured within HAL. For that matter, even the Mesa manual, which is usually pretty good at providing info, seemed a little sparse on the subject.

From a first time integrator perspective, I know I'm in the 'drinking from a firehose' mode right now, which is fine. I expected that. I've stumbled and you guys have been great at helping out. I like doing self discovery but I don't feel too successful with it in this project. I'm still bumbling around with how one links the PLC to HAL, for instance. Take the limit (in my case, the home as well, although I'll back off to the index pulse) switches as an example. I know the HAL input pin. And I have set the INI file so it will look at the index pulse. But I get the feeling that the INI file is a fairly "dumb" file that is primarily used only for configuring HAL (lots of references in HAL to INI define variables, for instance). What I am quite certain I've missed is how to bind the physical limit switch pin to LinixCNC so that it is used for homing and over-travel detection.

I get the feeling like there must be a guide out there that has all of the signals that are needed by LinuxCNC. I could then bind these to the physical PINs within my specific system. Thus far, however, I haven't seen a comprehensive document that has that information. I must be missing something.

Alan

I think there are a large number of people using 7i77 cards, but probably only a small percentage of them are using the extra smart serial features (Modes 1,2,3...)

I am not using any of them on the 7i77 I have.

My impression of LinuxCNC and Mesa is that the both are really really cool and very flexible. So, I'm especially hopeful that this project turns out well.

Regarding not using the other modes. That is interesting as it seems to imply that most people are not using an MPG then? I'd have guessed that an MPG would be one of the most popular things out there and I think the default configuration for the 7i77 doesn't support the MPG (manual is not in front of me now). Is it that everyone is using a pendant based MPG (i.e. one that is coming in through the USB...)?

Alan

Homing (including homing to index) is built into LinuxCNC:

linuxcnc.org/docs/html/config/ini-homing.html

How the homing state machine works is determined by the (static) ini file homing parameters
( the ini file consists mainly of LinuxCNC setup parameters/constants )

Most of LinuxCNC motion control pins and parameters are in the motion module

man motion

Much of the hal file "bolierplate" consists of connecting physical I/O pins to LinuxCNC modules module pins
Physical I/O pin names depend on the actual connected hardware

For first time hal/ini file creation its usually best to use an example file or create a working file set with stepconf/pncconf
( That is unless you want to learn all about the hal and ini file setup at the beginning )