Appreciating feedback on my Masso G3 controller build PART2

[tmtoronto]

MX4660 driver wiring:

Power comes from the 48 VDC PSU through two pairs of POS+/NEG- wires into the two POS+/NEG- inputs

Stepper motor step/direction wiring follows that of the DB9 enclosure connectors: red=A+/green=A-/yellow=B+/blue=B-

I have ferrites on the step/direction wires from each motor

The DB9 black ground wires from the motors are connected to a set of five joined ground terminal blocks, which are connected back to the mains VAC ground terminal blocks

I temporarily have the MX4660 Estop+ and Estop- pins shorted with a wire loop until I decide how to connect them to the overall safety circuit

I have a DB25 cable connecting the MX4660 to a screw terminal breakout board for ease of wire connection. I also added a ferrite to this cable

I connected pi #25 on the breakout board to one of the shared common terminal blocks

MX4660 driver/stepper motor related suggestions/guidelines I tried to follow:

1. Do not exceed the voltage rating of the driver. I chose a 48VDC to stay below max rating of 60 VDC
   
2. Provide enough amperage for the motors. I chose 12 Amps which is over 2/3s of peak (12A / 4.2A X 4)
   
3. Provide common ground termination point for motors
   
4. Provide electrical noise protection using ferrites on motor/component signal wires
   

MX4660 driver/stepper motor related questions:

1. I already asked a question regarding how to wire the MX4660 estop with the Masso, and have it part of my safety circuit thank you for those who responded. I have yet to decide what to do.
   
2. I have connected a wire from Pin #15 on the MX4660 which provides a 5V Fault signal that can warn if any of the 4 driver modules are in protection mode (e.g.; over current/voltage). What is the best way to connect this to the Masso.
   
3. Could Pin #25 on the breakout board instead be connected to one of the Masso GND(G) inputs? The manual has it as I have done - to the Masso power supply (-) common.
   

Masso G3 wiring:

Power comes in from the dedicated 24VDC PSU. The POS+ wire connects through a 1 Amp fast blow fuse terminal block to one of the PWR+ inputs of the Masso.

The NEG- wire connects from one of the shared common terminals to one of the GND (G) inputs on the Masso

The Masso S+ step signal outputs for the X, Y, Z, and B axes are connected to pins 2, 4, 6, and 8 respectively on the BB9 breakout board

The Masso D+ direction signal outputs for the X, Y, Z, and B axes are connected to pins 3, 5, 7, and 9 respectively on the BB9 breakout board

*Pin #25 from the breakout board is already connected to a shared common terminal block

I have connected an Estop button using one available NC switch. The POS+ wire from the Masso PSU terminal block connects to one terminal of the NC Estop switch. There is then one wire that connects the other terminal of the Estop NC switch to the Masso ESTOP input Pin #2.

MX4660 driver/stepper motor related suggestions/guidelines I tried to follow:

1. Try to keep step/direction wiring short between the Masso and the MX4660 driver
   
2. Use the B axis on the Masso for a CNC that uses a pair of Y axis motors
   

Masso G3 wiring related questions:

1. Is using one large ferrite core around all 8 step/direction wires, as effective as using four smaller ones around each pair of step/direction wires?
   
2. I have read numerous posts about this but just to confirm Masso GND (G) Pins are actually common (NEG-) connections?
   

 

[cncnutz]

Hi TMToronto

I had a look and cannot see ferrites on the step and direction wires but I do see them on the Motor Phase wires. Are these the ones you are referring too.

Install an Estop relay to the ES output and connect the MX4660 Estop through this. You can use the MASSO Relay module for this.
https://docs.masso.com.au/wiring-an...n/e-stop#wiring-e-stop-output-signal-to-relay

You can connect the Fault output of the MX4660 to a MASSO input and configure it as the Z Axis motor alarm input. It should come to a halt if any axis gives an alarm so it doesn't matter which one you choose.

You can connect Pin 25 to one of the Black terminals on MASSO. They are the same point.
Just be aware that the Black and red auxiliary terminals are for low power applications, such as Ground terminal on stepper drives.
The red ones I would personally only use for the adding resistors to inputs to pull them high if needed. I would generally use the main power distribution terminals for powering things such as accessories.

All Black Ground terminals are connected together internally in MASSO so all black terminals are -ve.
All Red power terminals are connected together internally in MASSO so all red terminals are +ve.

I'm not sure about the ferrite you are installing. I'm guessing you are making a plasma and are trying to keep high frequency noise out of the system.
As such having your setup in a metal enclosure and keep your high voltage plasma leads away will help a lot. Ensure your Table is earthed in accordance with best practices to reduce electrical noise from the Arc.

Hope this helps

Cheers Peter

 

[tmtoronto]

Thank you again Peter for your insights.

I did not have the ferrites attached yet - I am deciding on whether to use one around all Step/Dir wires, or use four - one each around ear pair. The electronics are mounted on a back panel which is being installed in a proper metal enclosure.

I do plan on using a relay to disable the driver - thank you for confirming its use. I am still trying to decide whether it is best practice to have a relay/contactor cut AC power to the MX4660 PSU, or if it is better to use it to cut DC power to the driver. I am not sure if you have any recommendation on this. Once I decide I can purchase and wire the correct components.

Thank you for confirming my understanding of the naming and internal connection of PWR and GND of the Masso G3.

Regards,

Tom

 

[cncnutz]

Hi Tom,

Do not use a relay or contactor to cut the AC or DC power to the drive.
Disconnecting the AC power is not the way to stop motor drives. Power them up and leave them powered up until you are finished and turn the machine off.
Never ever ever disconnect the power on the DC side of a stepper drive and especially when the motors are in motion. Doing so will more than likely destroy the drive.

Please use the drive disable function to stop the motors in an emergency as I mentioned above. That is what it is for.

Cheers Peter

 

[tmtoronto]

Thank you Peter for the warnings.

I was basing my understanding, in part, on this forum thread:

E-stop wiring, which way is correct?

I know this has probably been beaten to death but I haven't been able to find a solid answer. I am building a hobby CNC of my own design and am working

www.cnczone.com

Also,

Which of these two are you referring to when you mention the drive disable function?

Install an Estop relay to the ES output and connect the MX4660 Estop through this. You can use the MASSO Relay module for this.
https://docs.masso.com.au/wiring-an...n/e-stop#wiring-e-stop-output-signal-to-relay

or...

You can connect the Fault output of the MX4660 to a MASSO input and configure it as the Z Axis motor alarm input. It should come to a halt if any axis gives an alarm so it doesn't matter which one you choose.

When in the document it states:

CAUTION: This output must be used to control a relay and then the relay must be able to disable all drives and actuators on the machine. The user should not rely on the software to stop the axis, spindle or other actuators in case of an emergency and must disable all drives electrically.

I thought the "The user should not rely on the software to stop the axis, spindle or other actuators in case of an emergency and must disable all drives electrically." statement meant that disable drives electrically meant power to the driver, or by this does it mean using the functionality within the controller (Masso) and driver (MX4660) to disable all drives electrically?

Thank you,

Tom

 

[cncnutz]

Hi Tom

In the case of the Fault output on the MX4660 it is the drive that is signaling MASSO that there is an issue so I would assume that the drive has already stopped and the fault indication will tell MASSO to stop.

I am talking about the Estop condition where you either press the Estop or MASSO is alerted to an alarm that requires an Estop. Maybe a spindle alarm or a Plasma torch break away etc.
Disabling a stepper drive means disabling it using the devices built in disable function. It doesn't mean disconnecting power from the drive.
Spindle VFD's normally have a disable or Estop input to bring them to a halt so that is what you would use.
Some devices such as Routers and coolant pumps usually use relays to turn them on and off and won't have disable inputs on them. The input signal could be removed from their relays or power could be cut to these devices through a contactor / relay.
In general where a device has a built in disable function that is what you would use. If it doesn't then you would choose the best option for your setup.

Hope this helps
Cheers Peter

 

[tmtoronto]

As always it very much helps.

Thank you again Peter.

 

[zombieengineer]

Just some background information on why the "Disable" is preferred to "Power Cut".

Depending on the implementation of disable/E-stop the driver could effectively be shorting the motor phases resulting in a dump of rotational energy (rotational energy is converted into heat in the windings - basically hitting the brakes). In the "power cut" situation the rotational energy is only lost by mechanical friction - therefore takes longer to stop. In a shutdown situation you want to get energy out of the system as quickly as possible.

If you have an unconnected / loose stepper motor then you can compare how easy it is to turn the shaft with the windings open circuit versus the windings connected together.

 

[tmtoronto]

That explanation makes sense, thank you for taking the time to add to the conversation.

Tom

 

[halfstep]

I see you have everything mounted to a panel. What size is your enclosure? What kind of enclosure are you using? How are you planning to run your wires from inside the enclosure to outside the enclosure?

 

[tmtoronto]

Thank you for your interest, I hope the following helps:

I was able to source my enclosure from a company that sell used industrial equipment.

It is a 1420E7 from Hammond Manufacturing (24"Hx20"Wx7.5"D)

It and the mounting plate are made of high gauge metal. It has a low NEMA rating as it will be used in my basement shop.

I want to be able to completely disconnect everything for ease of maintenance/upgrade, so all planned cable connectors will be panel mount:

The VAC power cord plugs into a power module

The stepper motors are attached to DB9 connectors

The sensors, machine side Estop, probe, etc will attach using GX 16 connectors

When I eventually upgrade to a water cooled spindle, all its cabling as well will be through panel mount connectors

I am happy to provide pictures as my work progresses.

Tom

 

[halfstep]

That's a good size enclosure. I used a couple of Hoffman enclosures. I used a large enclosure for all the electronics and a smaller enclosure for the VFD. I kept the VFD separate from everything else to reduce any EMI/RFI. I also used some aviation (gx-16) connectors for going thru the enclosure. I also used some shielded sub-panel connectors from L-Comm for the USB and DB style connectors for the pendant and monitor. I used a lot of shielded cables wherever I could. L-Comm has a lot of good stuff for thru-panel mounting. I mounted most everything on DIN rails also. Post plenty of pics of you work in progress.

 

[tmtoronto]

It was my original intention to put the VFD in its own separate enclosure, but then I found this used panel at a great price. I think with careful placement I can have an all-in-one enclosure - others have done it - but I will just need to be careful with the added EMI/RFI it will introduce. I am sure you yourself have found how quickly the cost of these components adds up. I will use grounded shielding on the sensor cables in and out of the enclosure. I am relying on what I hope was thoughtful planning, as well as twisted wire pairs and ferrite cores, for my final build (-VFD for now) to resist signal interference. I added L-Comm to my growing list of bookmarks - thank you for providing that resource.

I will definitely keep sharing, as the help I have received on this and other forums has proved invaluable. I just won't show pictures of me trying to safely and neatly cut the openings for all the (non-circular) through panel connectors. The enclosure is 'robust' to say the least.