1 Axis Stepper Motor Turns in 1 Direction only

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JSimms
Posts: 3
Joined: Mon Aug 22, 2022 2:08 am

1 Axis Stepper Motor Turns in 1 Direction only

Post by JSimms » Mon Aug 22, 2022 3:13 am

I am using a KFLOP and KSTEP to drive 4 stepper motors. My motors are connected directly to the KSTEP board. Motors connected to channel 1, 2 and 3 work with no issue. When I perform tuning, they turn in both directions as they are supposed to. I can save the parameters for those motors and jog them with the KMotionCNC software in either direction. Channel 0 will only move in one direction. When I run the "Move" procedure on the Step/response screen, the motor will move slightly then stop and the next move continues in the same direction instead of returning back to the starting point. It seems like that channel is not getting a DIR input.

To troubleshoot I swapped the motor I had connected to channel 0 with the motor I had on channel 2. The issue stayed with channel 0, eliminating an issue with motor or wiring. I am thinking Channel 0 has a hardware problem. Can you provide any advice on what to check on the board and if there are any parts that could fail that are replaceable that may impact DIR command?

I bought these boards in June of 2021 and they have been sitting until now unused. I just had time to start wiring my equipment.

My KFLOP version is 4.34. The KFLOP board is connected to the KSTEP board with the ribbon cable that was provided (JP7 on KFLOP to JP36 on KSTEP).

As far as power supply goes, I have an external +5VDC supply for board power that is connected through the MOLEX connector on the KFLOP board. I am using a 48VDC power supply for supply to the motor power connector of the KSTEP board. Voltage Clamp setting configured for 49V.

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TomKerekes
Posts: 2003
Joined: Mon Dec 04, 2017 1:49 am

Re: 1 Axis Stepper Motor Turns in 1 Direction only

Post by TomKerekes » Mon Aug 22, 2022 6:04 pm

Hi,
When I run the "Move" procedure on the Step/response screen, the motor will move slightly then stop
Could you elaborate? How far is it commanded to move? Does it move the amount commanded? Is it stalling such that it continues to vibrate but not progress along the move?

Is the holding torque normal?

You might check the ribbon cable between KFLOP and KStep that it is not completely inserted or damaged. You might also ohm it out with a meter that all connections are present.

Is the Velocity and Acceleration for axis 0 set the same? If you slow it down does it behave differently?
Regards,

Tom Kerekes
Dynomotion, Inc.

JSimms
Posts: 3
Joined: Mon Aug 22, 2022 2:08 am

Re: 1 Axis Stepper Motor Turns in 1 Direction only

Post by JSimms » Tue Aug 23, 2022 1:34 am

Tom,

The "Move" is normal. It moves as far as it is supposed to. The motor does not stall. What I was explaining was that the normal process that I saw when running the "Move" function was a move in one direction followed by a brief motor stop followed by reverse motion back to the starting point. Channels 1, 2, and 3 all behave this way which is correct.

Channel 0 moves in one direction followed by a brief motor stop followed by motor movement in the same direction as the first move rather than returning to the starting point. No stalls or abnormal noise. If I increase the time or size on the step response screen, the motor moves a longer distance but the result is the same...both moves are in the same direction. It seems that the step pulses to the driver are correct but there is no direction control on channel 0.

When in KMotionCNC with Channel 0 configured as "X" axis, I can jog the motor but it always moves in the same direction regardless of what X jog button I press (i.e. + jog and - jog both move in the same direction for that axis only).

I removed the ribbon cable tonight and checked continuity. All pins checked good with 0 Ohms.

Below is the configuration I currently have on channel 0. When I moved the motor during troubleshooting to channel 2, I copied all of these settings also so I know these settings work with my motor from motion confirmation I did while connected to axis 2:

ch0->InputMode=NO_INPUT_MODE;
ch0->OutputMode=STEP_DIR_MODE;
ch0->Vel=7000;
ch0->Accel=700000;
ch0->Jerk=7e+06;
ch0->P=0;
ch0->I=0.01;
ch0->D=0;
ch0->FFAccel=0;
ch0->FFVel=0;
ch0->MaxI=200;
ch0->MaxErr=1e+06;
ch0->MaxOutput=200;
ch0->DeadBandGain=1;
ch0->DeadBandRange=0;
ch0->InputChan0=0;
ch0->InputChan1=0;
ch0->OutputChan0=8;
ch0->OutputChan1=0;
ch0->MasterAxis=-1;
ch0->LimitSwitchOptions=0x100;
ch0->LimitSwitchNegBit=0;
ch0->LimitSwitchPosBit=0;
ch0->SoftLimitPos=1e+09;
ch0->SoftLimitNeg=-1e+09;
ch0->InputGain0=1;
ch0->InputGain1=1;
ch0->InputOffset0=0;
ch0->InputOffset1=0;
ch0->OutputGain=1;
ch0->OutputOffset=0;
ch0->SlaveGain=1;
ch0->BacklashMode=BACKLASH_OFF;
ch0->BacklashAmount=0;
ch0->BacklashRate=0;
ch0->invDistPerCycle=1;
ch0->Lead=0;
ch0->MaxFollowingError=1000000000;
ch0->StepperAmplitude=20;

ch0->iir[0].B0=1;
ch0->iir[0].B1=0;
ch0->iir[0].B2=0;
ch0->iir[0].A1=0;
ch0->iir[0].A2=0;

ch0->iir[1].B0=1;
ch0->iir[1].B1=0;
ch0->iir[1].B2=0;
ch0->iir[1].A1=0;
ch0->iir[1].A2=0;

ch0->iir[2].B0=0.000769;
ch0->iir[2].B1=0.001538;
ch0->iir[2].B2=0.000769;
ch0->iir[2].A1=1.92076;
ch0->iir[2].A2=-0.923833;
EnableAxisDest(0,0);

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TomKerekes
Posts: 2003
Joined: Mon Dec 04, 2017 1:49 am

Re: 1 Axis Stepper Motor Turns in 1 Direction only

Post by TomKerekes » Tue Aug 23, 2022 4:46 pm

The settings seem correct. Have you flashed anything to KFLOP? If so remove it by flashing 'New Version"

It seems likely the problem is with KStep. Is there any contamination or corrosion on the board?

If you are capable of troubleshooting the Axis 0 Direction Signal:

Enters via JP36 pin 16 (relative to KFLOP GND)
Connects to resistor R71 - Pin2 exits R71 Pin 6
Enters optocoupler U23 Pin 4 exits Pin 6 (now relative to KStep GND)
Connects to Stepper Controller U17 Pin 30

I suppose the other possibility is that KFLOP IO Bit 9 is not working. You might check it using the Digital IO Screen. Also when when performing the forward/backward move does Bit 9 toggle on the Digital IO Screen?

Otherwise contact our support and we can offer a 25% discount on a replacement.
Regards,

Tom Kerekes
Dynomotion, Inc.

JSimms
Posts: 3
Joined: Mon Aug 22, 2022 2:08 am

Re: 1 Axis Stepper Motor Turns in 1 Direction only

Post by JSimms » Wed Aug 24, 2022 1:53 am

Tom,

Thanks for the feedback. I had flashed data to the KFLOP. I removed that data by flashing with "New Version" as recommended. The issue of movement in 1 direction persisted even after doing this on channel 0.

I don't see any corrosion anywhere on any pins/contacts.

I dug into troubleshooting Axis 0 direction signal without power with my meter. I started checking continuity through the ribbon cable (pin 16) to R71 then on to U23 pin 4. When I got to U23, pin 4, I could only get conductivity by pressing down on pin 4 pad with my meter.

I then applied power and tried to execute the "Move" command again. I can get channel 0 to move in both directions by pushing down on pin 4 pad with my meter probe while executing the "Move". My thought is the solder connection or the pin is NG at pin 4 on U23. Can I send this in for repair? I don't have proper equipment to solder that pad back (or replace U23 depending on actual issue) without risking short to another pin.

I did check the I/O monitor and I can see the IO9 state changing from on to off during the move command. I have not tried to confirm any voltages on the board to verify the signal is high/low. Since I was able to get it to reverse by messing with pin 4 on U23, I don't think voltage checks are necessary at this point.

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TomKerekes
Posts: 2003
Joined: Mon Dec 04, 2017 1:49 am

Re: 1 Axis Stepper Motor Turns in 1 Direction only

Post by TomKerekes » Wed Aug 24, 2022 5:54 pm

Contact support @ dynomotion dot com for an RMA number.
Regards,

Tom Kerekes
Dynomotion, Inc.

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