Dec 16, 2012

Troubleshooting the Baldor Servo Drives - Basic Things to Remember

We have discussed in detail about the Baldor servo drives earlier and also a full learning series on Mint workbench. Generally, we face a lot of problems in troubleshooting the servo drives. In this post, we are going to discuss some of the useful points which we should keep in our mind while working with Baldor servo drives.

Troubleshooting the Baldor Servo Drives.png

Troubleshooting Common Problems of Baldor Servo Drives

Well, there can be many problems while working with servo drives, so we have divided this post into 5 different sections according to the type of problems.

1. Solving Serial Communication Problem in Servo Drives

*Check the controller has logic power supplied. The Status display should be active and the internal fans operating (on some units fans do not operate until the controller is enabled). The controller must have a logic supply connected to enable communication over the serial port. The logic supply is connected at X1, or internally generated from the AC supply (depending upon model).

* Try power-cycling the controller. This will reset the controller's serial drivers and may allow communication.

* Check the controller is properly earthed/grounded

* Try an alternative serial cable and/or confirm that it can be used to establish communication with another Baldor controller.

* Confirm that the PC's serial port is operating correctly

2. Drive enable problems - Drive is not enabled

*On FlexDriveII, Flex+DriveII or MintDriveII, confirm that front panel DIP switch 8 (enable) is set to the ‘On’ position to allow the drive to be enabled. To check that the firmware can detect the operation of this switch, check the Spy window's Axis tab where the state of the enable DIP switch is displayed. Alternatively, use the Command window to check the value of ENABLESWITCH.

*On FlexDriveII, Flex+DriveII or MintDriveII, check the setting of DRIVEENABLEMODE. Unless mode 1 or 2 has been selected, it will be necessary to enable the controller using DRIVEENABLE.

*Check the drive enable input is correctly wired and +24VDC is present.

*Check that there are no initialization errors which may be preventing the drive from being enabled.

Recommended Article: PLC Programming For Counting Encoder Pulses

3. Drive error Problems

* DRIVEERROR bit 0 (Powerbase fault) or bit 1 (Coprocessor) is reported.
This error indicates that the DSP processor has detected an interprocessor communications fault; this should not occur. If the problem persists, contact Baldor Technical Support.

* DRIVEERROR bit 2 (Current fault) or DRIVEERROR bit 3 (Overspeed) is reported.
If this error occurs when using a resolver motor, check the feedback cable. If the cable is not connected or there is an intermittent signal, the motor will run in an uncontrolled manner and cause an over speed or overcurrent trip. If this error occurs during a high acceleration motion profile, check the setting of DRIVESPEEDFATAL, the over speed trip value.

Use the Monitor tab and Scope mode to capture the move profile and establish what sort of overshoot is occurring on measured speed. Overshoot is typically the result of inappropriate gain terms or a high acceleration profile.

4. INITWARNING problems in Baldor drives :-

* INITWARNING bit 0 (Non-volatile RAM invalid) is reported. The contents (one or more elements) of NVRAM is corrupt. Use NVLONG and/or NVFLOAT to establish which element is corrupt, then write a new value back to those elements or reset the entire array using NVRAMDEFAULT.

* INITWARNING bit 1 (unknown PLD version) is reported.

5. Miscellaneous problems of Servo Drives :-

Well, there can be situations that you are facing some problem which we have not discussed above and you are not able to solve it. So it may also happen but never give your hope. A good PLC engineer should try his level best until the issue is resolved.

If still there is the problem in the servo drive then check the below points.

Use the Monitor tab and Scope mode to capture the Measured Velocity, Demand Velocity, Effort and Drive Bus Volts during the move profile. If the move is a MOVEA or MOVER command, and the plot of Demand Velocity is a triangular shape, the length of the move is not sufficient to reach the slew speed (SPEED) using the current settings of ACCEL and DECEL. Increase ACCEL and DECEL to allow the move to reach the intended slew speed. A longer move will also be more likely to reach the slew speed.

If the plots show that Demand Velocity reaches DRIVESPEEDMAX, but Measured Velocity does not inspect the plots of Effort and Drive Bus Volts.

We are sure that after reading you must have increased your knowledge base about the servo drives. Keep visiting for more updates and don't forget to like us on Facebook. Subscribe to Automation-Talk by Email.

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