Jog mode output?

[johnno402002]

Hi,

I'm retrofitting a milling machine with a Masso controller, replacing Mach3 and a usb motion card. Here is a video of the machine

I'm trying to retain as much of the original manufacturers design as possible, and there has been a couple of things that are causing some complication in setting up the Masso.

The homing and limit switches are the first one. The machine is set up with the normal homing switches on each axis, and on the x and y axis it has two additional switches, one at each end of the travel. On the z axis it only has a limit switch at the top, nothing at the bottom where the head would hit the table. So eight switches in total, with the homing switches inside the limit switches.

When using the machine with Mach 3 I did get into the limit switch zone a couple of times, which halted the axis drives. To get back out of the limit, the manufacturer has a limit override button on the machines front panel which allows you to jog the machine back from the limit. This worked ok on mach3, and I'd like the same thing on the masso if I can get it. To manually move this machine back from the limits requires covers to be removed, and an extra elbow in my arm would be handy as well.

I've decided to use a very basic PLC I already have to handle the logic for the limit switches, and for the drive enable stuff, and a few other bits and pieces.

To make the back out process a little more idiot proof, I was wondering if it is possible to get an output from the Masso indicating what mode it is in, so that I can make the axis limit override only possible in Jog mode?

John

 

[tayloredtech]

Hi John,

I may have missed something here but if you have traveled into a limit I would have to assume the software has lost track of the position of your CNC and would have to be homed to recalibrate. Simply backing off a limit isn't going to resolve the issue that cause the machine to hit the limit.

The Masso has soft and hard limits which can be overridden in settings but are there for safety of the equipment.

Mitch

 

[johnno402002]

Hi Mitch,

Thanks for taking the time to reply, and happy new year!

Yes, in order to hit one of the hardware limits the software has lost the position of the machine, or the software limits are set wrong. I believe the reason the original designer of the machine added the extra hardware limit switches is to protect the machine from this loss of position. I'm guessing he had experienced the problem at some point. Backing off the limit wont fix anything, but you still have to back off the limit at some point to investigate the problem. If the hardware, in my case here the plc, has the drives disabled, I have to override this in order to back away from the limit. Of course, once the limit is overridden, it's quite possible to drive the machine the wrong way and damage it, but I wouldn't do that again, surely <sigh>.

I see in the alarms video that using the Masso alone I may be able to home the machine and it would lift the disable on the axis drives and attempt to drive it home, but the video is not clear on the need to move the machine back from the limit, and I have not tested this yet. The Masso hardware limit design seems to have the limitation of only using the single homing switch as the hard limit. The other end of the axis only has software protection, and the redundancy of having both the homing and limit switches is lost at the homing end. I'm just not comfortable with that risk, or is it more capable than I'm seeing?

At the same time, I don't think the Masso should be stuffed full of all this logic stuff, because everyone needs something a bit different, and it's a fast path to feature bloat and multiplication of confusion. I think I like the Masso so much because its such a clean controller. Hence my question is it possible to get an output of the mode it is in, so I can work with it. Its not a big deal, just wondering if it is hiding there already.

John

 

[testyourdesign]

@johnno402002

In my experience it's usually better to start simple. I recommend that you focus on getting the basic functions of the machine running with Masso first. That way you can sort out any minor issues as they come up.

Masso accepts inputs from N/O limit switches at the opposite end of travel if you wire them in parallel with the homing switches . Once the homing procedure has been completed, Masso's logic considers any input from the home switch or limit switch as a hard limit input. You can always turn off soft or hard limits from the F1 screen if you know that the machine will work in the extended travel without damaging your limit switches.

I'd like to see that PLC setup if you can share a few pictures. Good luck with the build.

Cheers, Stephen Brown

 

[johnno402002]

Hi Stephen,

Thanks for taking the time to reply, I appreciate it.

A detail I failed to mention above is that the machine is fitted with 3 wire DC proximity sensors, N/O. The Omron documentation on these is saying to limit the number connected in parallel to three or so, with warnings of erroneous pulses etc. I started looking at using relays to isolate them from each other, and then had the thought that PLCs were invented to do this, and it could do a few other things while it was there. And there was one laying on the bench, which I had bought for my Son to mess about with and learn a bit about PLCs. I try to start simple, but it usually doesn't last long...

I do have the spindle running off the masso, and it is a great improvement over the previous JNC control card, which delivered a very dirty speed signal to the bldc driver. I could not get the spindle below 500 rpm reliably, below that it would start typing random characters into the mdi window on mach 3. Like a room full of monkeys, eventually it typed something the machine understood, and moved the x axis. I tried a lot of things to identify the source of the noise and reduce it, and I had some success but there were just too many layers of technology to find the problem. Then I heard about the Masso, and here I am. The Masso is driving the spindle down at 200 rpm without any trouble. Not sure if it has any power down there yet, but it is a big improvement.

I will post more details of the PLC etc when I have it running. This is the PLC https://www.automationdirect.com/ad..._(stackable_micro_brick)/plc_units/c0-00dd1-d

John

 

[tayloredtech]

Quote from johnno402002 on January 1, 2019, 8:01 am

Hi Stephen,

Thanks for taking the time to reply, I appreciate it.

A detail I failed to mention above is that the machine is fitted with 3 wire DC proximity sensors, N/O. The Omron documentation on these is saying to limit the number connected in parallel to three or so, with warnings of erroneous pulses etc. I started looking at using relays to isolate them from each other, and then had the thought that PLCs were invented to do this, and it could do a few other things while it was there. And there was one laying on the bench, which I had bought for my Son to mess about with and learn a bit about PLCs. I try to start simple, but it usually doesn't last long...

I do have the spindle running off the masso, and it is a great improvement over the previous JNC control card, which delivered a very dirty speed signal to the bldc driver. I could not get the spindle below 500 rpm reliably, below that it would start typing random characters into the mdi window on mach 3. Like a room full of monkeys, eventually it typed something the machine understood, and moved the x axis. I tried a lot of things to identify the source of the noise and reduce it, and I had some success but there were just too many layers of technology to find the problem. Then I heard about the Masso, and here I am. The Masso is driving the spindle down at 200 rpm without any trouble. Not sure if it has any power down there yet, but it is a big improvement.

I will post more details of the PLC etc when I have it running. This is the PLC https://www.automationdirect.com/ad..._(stackable_micro_brick)/plc_units/c0-00dd1-d

John

I understand where you are at. I did this with my original DIY CNC. I had home limit switches and Hard limit switches with seperate inputs. One thing you could do as you are setting up is to wire the extra sensors into masso seperately and set them up in settings as OTHER alarms. such as spindle alarms, in line with a N/O estop connection, air pressure sensor etc which all will stop the machine UNTIL- you have everything resolved in driving the machine accurately and don't need these anymore.

Eventually they will add sensors for other limit/ home based sensors for these scenarios but since getting my machine up and running correctly I haven't had the ability for anything to hit a limit without Masso knowing about it. Always make sure you have 2 boxes ticked that after an E-stop OR limit is hit the machine has to home itself. This way on machine boot up it will head home and be ready to play ball

Mitch

 

[johnno402002]

Thanks Mitch, much appreciated.