ClearPath Axis?DriveOk error

[Richards]

I'm running v4.20. I rewired my test bench, removed the AutomationDirect PLC and wired the Acorn to directly handle Axis?DriveOK faults (with ? being 1, 2, or 3). The ClearPath motor asserts the HLFB signal when the servo is on and the servo is not in a fault condition. I've assigned Axis1DriveOK to input 1, Axis2DriveOK to input 2 and Axis3DriveOK to input 3. I've tried Motor Axis Fault Delay Time values ranging from 1,000 msecs to 5,000 msecs. I have NoFaultOut assigned to output 3. Output 3 controls the coil of the contactor that controls power to a linear 70VDC power supply.

When I power up the Acorn and cycle reset, I get a green light on output 3 and the motors get 75VDC. If I push cycle start, I get an immediate motor fault (random, sometimes Axis1 somethings Axis 2 or Axis 3). This is with the Axis Motor Drive fault delay time set (currently) at 5,000 msecs. If I wait a second or two after cycling reset before I press cycle start, there is no Axis?DriveOK fault.

It seems to me that the Acorn should not check for a motor fault until the Axis Motor Drive fault delay time has expired.

Report is attached.

report_7804733AD12A-1224192773_2020-01-09_04-13-40.zip

(265.91 KiB) Downloaded 85 times

[Gary Campbell]

Mike...
Are the Clearpath ENA- wires connected to the Acorn ENA terminals? If so, try connecting them to 24v COM (-)

[Richards]

Gary,
Thanks. I was a little groggy when I posted about the problem, or I might have seen the F2/F3 Enables just blinking On/Off whenever I had an axis fault. As soon as I read your post, I did the head slap thing and followed your advice. Instead of hooking the motor enables directly to Common, I'm running the common signal through the contactor that controls the 75VDC power supply. That way, if there is power to the servos, the motors are also enabled.

The Acorn NoFaultOut signal directly controls the contactor to the 75VDC power supply. I think that I'll add a self-latching relay circuit in series so that I manually control when that power supply is turned on. In the event of a motor fault or E-Stop, the 75VDC power supply is shut off; however, as soon as the E-Stop is reset, that power supply is turned back on. Although that should be okay with this test setup, I think that needing to push a button after the NoFaultOut signal goes active would be better; that way, regardless of what caused the NoFaultOut signal to go inactive (and active again), I wouldn't end up with a contactor that chattered On and Off and I wouldn't end up with a fried power supply or fried motors from cycling the power supply too quickly or too frequently.

[Gary Campbell]

Mike...
Yes, a latching circuit is best. Many contactors have a low current NO set of contacts for that exact purpose

[Richards]

Here's a photo of the basic bench. The latching circuit has been installed. The actuators are just lying sideways on the front of the bench (Green, Indicator LED, Red). When the Acorn asserts the NoFaultOut signal on Relay Output 3 and I press the Green On actuator, the 75VDC power supply turns on. (The power supply is on the other side of the panel. It's just a toroidal supply for now. The IPC-5 supplies are on the shelf until I get everything functions properly.)

This setup has the servo motors' enable signal connected to the contactor that controls the 75VDC power supply. The Enable signals are automatically asserted if that power supply is on. It works, but it's NOT what I had in mind and it's not the way I had things working when I used the CLICK PLC. When I had the CLICK PLC attached, I generated a false DriveOK signal before turning on the 75VDC power supply. The false signal allowed the Acorn to assert its NoFaultOut signal. The CLICK used that NoFaultOut signal to turn on the 75VDC power supply. The ladder logic turned on an internal timer when the 75VDC power supply was started. When that timer timed out, THEN the CLICK monitored the actual HLFB signal from each of the servo motors. If a motor faulted, the CLICK notified the Acorn via the DriveOK signal and the Acorn stopped everything, including the NoFaultOut signal. At that point the 75VDC power supply was turned off. The servos stopped. The Acorn waited for a manual reset before continuing. It sounds a little complex, but it's only a few lines of ladder-logic. I may have to put a minimal CLICK PLC back into the system so that the Acorn's Enable signals control the enable signals on the servos and the E-Stop OR a HLFB fault shuts down the motors. I can see lots of testing before I decide.