Change HS output pulse width

[Garyhlucas]

We are using step and direction output on a BR-DM1E-36ED13D to run a Clearpath servo motor with a maximum step rate of 80Khz. However we have long cables between the drive and the PLC, about 30 ft.  Cable is shielded.
Tecnics recommends a wider pulse width for long cables and the motor occasionally faults with an error the manual relates to pulse width.
Can we change this?

[Controls Guy]

The duty cycle may be fixed at 50%.   You might have to change your resolution per step & go with lower frequency.  Is that feasible?

[Teknic.Servo]

Hi Gary,

It sounds like you are experiencing a "step input timing" shutdown on ClearPath. This error can be caused by a few different things, one of them being the step pulse time/width. Since you are only using a frequency of 80 kHz (ClearPath's inputs can accept up to 700 kHz), I'd recommend trying some other troubleshooting items as well. (As a note, I am not familiar with the specific controller you are using, so some of these may not apply.)

-Ensure that the controller is outputting more than 4VDC reliably to ensure that it is always asserting ClearPath's optically isolated inputs.

-Confirm what type of outputs your controller has. If the controller uses open collector outputs, make sure that the resistor specified in the ClearPath manual is installed correctly. Generally, this will only affect machines with cable runs longer than 10ft, however, in applications with a large amount of electrical noise (such as plasma cutting applications) the resistors may be needed on shorter cable runs. I know you mentioned that your cables are 30ft, but I figured this information may be helpful to include in case anyone else comes across this post.

-Make sure that the wiring to the ClearPath inputs maintains a separate signal pair  for each ClearPath input.  The "step input timing" error can sometimes happen when a controller doesn't have enough connections for V+ and GND and the positive and negative signals get separated within the electrical cabinet.

-As a general rule, try and ensure that the 5-24V power supply used for the ClearPath inputs is only used as a logic power supply and is not being used to power other inductive loads such as: large contactors, solenoids, small DC motors/fans, heaters, etc.

-This last bullet won't apply to you since you are using an 80 kHz output frequency, but the error can also occur if the controller's maximum step pulse frequency is higher than 700kHz or if the minimum step pulse time is less than 715 nS. These settings are typically configurable in the controller (which I think is what your original question is asking about).

Please feel free to give Teknic a call (585-784-7454) to help with troubleshooting if you try all of the above and are still experiencing issues (or if you have any other questions). You can also contact us at https://teknic.com/contact/

Best regards,
Bridgette O. - Teknic Servo Systems Engineer

[Garyhlucas]

I want to let everyone know we solved the comm faulting issue. Isolated power supply didn?t help. What worked was using 1K 2 watt pullup resistors on the Step and Direction inputs, as recommended in the user manual for the servo motors. Flawless operation after that.