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External drivers 2HSS86H in parallel

From the original Synthetos forum (2011–2025)

Started by pereira.newton on in TinyG Support. 5 replies, last activity Aug 2, 2020.

pereira.newton #

Hi Guys,

Below is my setup

I had purchased 2 Tinyg V8 motors to build a CNC. I don't know why I bought 2, though I might accidentally destroy one hence I guess I got 2.....

I have build a CNC using Tinyg V8, external drivers 2HSS86H Hybrid Step Servos, and Nema 34 motors.

The CNC configuration is X1X2YZ

Motor 1 - J17- connected to 2HSS86H to motor Nema 34 "X1"
Motor 2 - J18- connected to 2HSS86H to motor Nema 34 "X2"
Motor 3 - J19- connected to 2HSS86H to motor Nema 34 "Y"
Motor 4 - J20- connected to 2HSS86H to motor Nema 34 "Z"

I'm facing a few issues:

Issue 1:

Motor 4 - J20- connected to 2HSS86H to motor Nema 34 "Z" doesn't work. The motor doesn't rotate.

I know the driver and motor works since I swapped it with the Y and it was rotating.

Not sure where or how should I fix this. Is there something in the Tinyg I need to update\change to get it to work?

Issue 2:

I read on the forum that we can conned 2 drivers in parallel to one of the "JXX" pins to drive 2 external drives form one JXX pin thus freeing up a port, which I did the following

I took the wires(Step, Direction, Enable) from J17 and connected it to 2HSS86H -"X1" and to 2HSS86H -"X2".

but only X1 rotates and X2 doesn't.

I know that the driver and motor work since I tested them independently
and it worked.

So not sure where and how do I fix this.

Goal:
1) I'm trying to get the Z axis working with the to 2HSS86H to motor Nema 34 "Z"

2) I would like to connect the "A" axis to my current X1X2YZ setup, hence I need to free up one port, by combining X1 and X2

Please can you guide me to reach my goal.

Regards
Newton

PS: I have the data sheet for the driver 2HSS86H if it's needed.

cmcgrath5035Staff #

Sorry for ignoring you of late, for some reason the automatic notification of a post I have set up has not been sending of late.

I see from other posts you have been digging in to some of the legacy traffic related to output pulse width.

I'll also assume that You issue 2 has the objective of creating an (X1X2)YZ machine as a workaround for the motor4 port (J20) not working with your external drivers.

Connecting two external drivers to J17 "should work".
Logically it will work if you can invert the logical operation of one of the external drivers, so one will be CW and the other CCW when commanded to move.

Assuming that your 2HSS86H units have opto isolated inputs, which are typical in this application, I'll suspect that the tinyG logic pins might not be able to source adequate current to properly operate the two opto-isolator ports in parallel. In logic terms, the Fanout (load capability) of the microcontroller output port that drive J17 might be inadequate current drive for the opto-isolator switches. On possible solution might be to bradboard a one input, two output buffer and level translator circuit to increase the Fanout of the J17 pins.

First, try your double load on all three of the outputs, J17,J18,J19.
One of those might have slightly higher drive capability. This is somewhat of a stretch, but easiest to implement. If J18 does work, for example, then build a Y(X1X2)Z machine.

AFAIK, most others solved this issue by finding external drivers that work, by trial and error.

Do you have a really heavy spindle load? I drive Nema32s on my XY1Y2Z machine directly from the tinyG driver devices, with Z being a NEMA27.
All this ver depended on the mass of your machine, of course.

pereira.newton #

Cool on it..... give me 2 days, will try out the recommendations and report back....

cheers mate!

cmcgrath5035Staff #

Good luck with it.
Just to reinforce, make sure that the X1 Driver and the X2 Driver individually connected to J17(or J18 or J19) work OK before connecting them in parallel.

pereira.newton #

hi @cmcgrath5035,

Following is my test case and results.

Test 1:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D1 - 2HSS86H) and Nema 32 Motor (M1)

Result: Motor M1 rotating

Test 2:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D2 - 2HSS86H) and Nema 32 Motor (M2)

Result: Motor M3 rotating

Test 3:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D3 - 2HSS86H) and Nema 32 Motor (M3)

Result: Motor M3 rotating

Test 4:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D4 - 2HSS86H) and Nema 32 Motor (M4)

Result: Motor M4 rotating

Test 5:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D1 - 2HSS86H) and Nema 32 Motor (M1)

Result: Motor M1 rotating

Test 6:
Connection: Motor 2 (J18) on Tinyg connect to Driver(D2 - 2HSS86H) and Nema 32 Motor (M2)

Result: Motor M2 rotating

Test 7:
Connection: Motor 3 (J19) on Tinyg connect to Driver(D3 - 2HSS86H) and Nema 32 Motor (M3)

Result: Motor M3 rotating

Test 8:
Connection: Motor 4 (J20) on Tinyg connect to Driver(D4 - 2HSS86H) and Nema 32 Motor (M4)

Result: Motor M4 does not rotating

Test 9:
Connection: Motor 1 (J17) on Tinyg connect to Driver(D1 - 2HSS86H) and Driver(D2 - 2HSS86H)

Result: Nema 32 connected to D1 moves, Nema 32 connect to D2 does not move.

Test 10:
Connection: Motor 2 (J18) on Tinyg connect to Driver(D2 - 2HSS86H) and Driver(D3 - 2HSS86H)

Result: Nema 32 connected to D2 moves, Nema 32 connect to D3 does not move.

Test 11:
Connection: Motor 2 (J19) on Tinyg connect to Driver(D3 - 2HSS86H) and Driver(D4 - 2HSS86H)

Result: Nema 32 connected to D3 moves, Nema 32 connect to D4 does not move.

Conclusion:
Test 1 to 4 proves the Drivers and Nema 32 Motors are all working.
Test 5 to 7 proves that J17, J18, J19 is able to drive the motor.
Test 8 proves that J20 is not behaving like its siblings (J17, J18, J19), not sure why and what's the cause of it. I have ended up not using J20, instead I'm replace the Nema32 with Nema17 and connecting Nema17 directly to the onboard driver.
Test 9 to 11 prove that 2 Driver 2HSS86H is not able to perform as expected when connected in parallel with the working J ports.

Comments:
1) Do you have a really heavy spindle load? - [Newton] No its a small spindle and all in all the weight would be 1-2kgs

2) I drive Nema32s on my XY1Y2Z machine directly from the tinyG driver devices - [Newton] please can you share your wire diagram or pics of your machine I will try to replicate it at my end.

3) I’ll also assume that You issue 2 has the objective of creating an (X1X2)YZ machine as a workaround for the motor4 port (J20) not working with your external drivers. - [Newton] No so currently the machine is using J17, J18, J19, and Motor4 on board driver to drive 4 motors, of these axis X1,X2,Y,Z. I want to connect the fifth motor to drive A axis. What are the options I have for connecting the 5th motor?

4) On possible solution might be to bradboard a one input, two output buffer and level translator circuit to increase the Fanout of the J17 pins. - [Newton] do you mean a level shifter? if yes then I have ordered a level shifter. I plan to supply the Low Voltage(3.3V) and High Voltage(12V) from the TinyG board. Would that work?

Request:
Please can you help propose a way forward. The end goal I have is to connect the 5 motor and have my machine configuration as X1,X2,Y,Z,A.
I really don't want to end up buying another\different controller, since I have 2 tinyg, of which 1 is still in its original packing. I would just end-up having to much hardware.

cmcgrath5035Staff #

RE: Comment 2) My X-Y1-Y2-Z machine does not use External Drivers. I have Nema 23 (not 32, sorry) motors on M1, M2, and M3 connectors. The M4 motor is a NEMA 17 which is more than adequate for my spindle.
My NEMA 23s are https://www.omc-stepperonline.com/nema-23-stepper-motor/nema-23-bipolar-1-8deg-2-4nm-340oz-in-1-8a-4-95v-57x57x104mm-4-wires.html low currrent 23's.

RE Comment 3) tinyG can assign X, Y,Z, A,B or C motion to any of M1-4.
If you want a 4 axis machine, one of the motion axes will have to drive two motors. So what you really want I'll call and X-(Y1 Y2) - Z - A. If Z and A both need to be NEMA32's, you will need to use external drivers, which is what you are attempting.

I am assuming that when you run Test 11, where D3 moves its motor and D4 does not move its motor, if you disconnect D3 and then D4 moves(operates). That indicates to me that the J19 port cannot source enough power to drive two inputs in parallel.

RE Comment 4) This possible issue with the logic interface to the external drives is both logic voltage (ports are 3.3V logic) and current drive (fan out capability). Implementing 3.3V to 12V level shifters should work, assuming the input voltage rating on your external drivers can handle 12V, which is true with most of the ones I have seen. Keep in mind that the inputs to the external drivers are typically a led emitter (~2V drop) and a series limiting resistor.

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