Arrow2 750 - Axis Puls enable alarm & X-Axis drive alarm

This machine is an Arrow2 750 (Acramatic 2100) with Siemens drives.

We are having an issue related to the x-axis drive

With the machine cutting or even sitting idle after alignment - we get an intermittent alarm "NCA - Axis pulse enable alarm" then subsequent "NCA - X-axis drive alarm". Alarm code on the Simodrive readout is A608

The machine may sometimes run all day or alarms out a few minutes after powering on and aligning the axis.

Both the Simodrive for x/z axis and x-axis motor have been sent out for repair/diagnostics, yet the problem still exists.

We've replaced the DP profi card due to an unrelated (or so I think) issue which caused the machine to fail boot diagnostics. The machine now boots and is operable until the alarm.

We've checked continuity and resistance through the com cable between the drive and the motor as well as the power lead with no obvious issues.

If the machine is idle and the rest of the shop is quiet you can here a harmonic hum noise coming from the end of the ball screw opposite the x-axis motor. When you go to manually move the axis it alarms out as described.

I have had similar issue. However that harmonic "hum" noise you speak of was much much louder on mine. That "hum" is called dither. That is the drive constantly jittering back and forth to hold position. Come to find out I had bad bearing in my axis on the ball screw. I replaced them and also had to "de-tune" the x axis drive a tiny bit so it wasnt so "sharp" in its movements. I had a Siemens tech come out to do that work. He looked over the entire machine and agreed my ball screws all inspected fine. He tuned the Z and X axis drives while he was here. The machine still runs to this day and that was a few years ago. I havent noticed any issue in the re-tuning of the drive. While I did all this work, I replaced both the encoder and power cable to the x axis motor as I had a very slight resistance in the encoder cable. I figured it couldnt hurt to replace it with a new cable while I had it all torn apart anyways.

I have an Arrow 2 1250C, so I think I have different drives then you. I will send you a PM soon regarding my drives. I hope this all helps.

We were speculating that the bearings may be causing some of the feedback. We also have an Arrow 1000 which as the harmonic balancing pack on the end of the ball screw and when replacing the bearings on that machine we learned how sensitive any feedback could be on the motor. Thanks for the input, the axis bearings will be 20 years old this year and while still quiet, probably in need of replacement.

Tachometer feedback brushes on the axis motors can cause issues with older DC Servo machines.

The "hum" you described could be from backlash. I have seen the coupling inserts on this vintage machine disintegrate causing a similar situation, but since you indicated the motor has been out already, I assume you would have checked/replaced the insert when it was out.

However, there are also many other possibilities. The A-608 alarm is essentially saying the axis has been at torque and current limits too long. There is a long list of possibilities for this to occur including motor, power cable, parameter settings, IR module, Mechanical issues, Encoder, Encoder cable, grounding, power section, control module, etc.

Quote:

---

Originally Posted by maver1ck

The "hum" you described could be from backlash. I have seen the coupling inserts on this vintage machine disintegrate causing a similar situation, but since you indicated the motor has been out already, I assume you would have checked/replaced the insert when it was out.

However, there are also many other possibilities. The A-608 alarm is essentially saying the axis has been at torque and current limits too long. There is a long list of possibilities for this to occur including motor, power cable, parameter settings, IR module, Mechanical issues, Encoder, Encoder cable, grounding, power section, control module, etc.

---

Correct, we have replaced the insert, all looks good there. The ball screw moves easily when turned by hand. The motor and drive were sent to Global Electronics for diagnostics and repair. I was sure to instruct them not to lose any perimeters set in the drive and I have to trust that they did not. We had the same issue before the motor and drive were sent out but had other issues on top that we have finally worked out. We've checked for shorts through the power cable and encoder cable as well as continuity and resistance through both with nothing looking out of the ordinary, although we are by no means experts when it comes to diagnostics.

So an update on this. We have now replaced the ballscrew assembly and x axis bearings but still having the same X-axis pulse alarms with A607 and A608 error cods on the drive. I've swapped the x+z drive with the spindle drive (same part numbers) to see if the error would move to that axis but error remains on X-axis. Mechanically the x-axis is new at this point, the machine moves freely and easily by turning the ballscrew by hand.

Is there a simple way to tune the drive/motor to be less sensitive? As a way to eliminate the scales as a possibility, we thought about also disabling the scales to have the machine locate by encoder but was unable to do this through the axis settings (our Arrow 1000 has scales disabled from what we were told) as it said that x and y must be "distance coded"

PensFan1028, The 611U Drives consist of a two axis controller card which has a memory module with the parameters for each axis. Below this is the Power Module with the power transistors. You can swap Controller cards; but only if the part Number is identical and you must keep the memory module with the same power module and motor! There is no way the Spindle Power Module and the X/Z Power Module are the same amperage and part number.... the A608 is a Speed controller output limited on channel (A=X-axis): Cause The speed controller is at its limit for an inadmissibly long time (torque or current limit). You have a bind, shorted motor, or broken motor lead, or a bad power module. Make sure that the fans on the bottom outside the cabinet are running to keep the transistors cool and prevent damage. I would disconnect the motor leads and Ohm each to the other and to ground. I would Mega-Ohm the motor leads to ground. If the leads are hooked up wrong it will go into an over-current immediately. If the Oms and Mega-Ohm are good and all connections are correct and tight; it would be a bad Power Module, incorrect parameters, or bad Controller Card.
GregW