Common Causes of Unexpected Behavior/ Errors

Common Causes of Unexpected Behavior/ Errors

Postby ToddR » Wed Apr 21, 2010 3:54 pm

Here are a few simple things to check if your Adept ePLC controlled robot is not moving to the exact location you expect, or you are experiencing *position out of range* or *obstacle collision* errors.

1) Error -3007: *Invalid command: More than one command bit enabled*
If, for example, you attempt to move the robot while locations are being written to the controller, the location may be written in error, causing the robot to either 1) move to an unexpected location 2) return the *position out of range* error, or 3) return the *obstacle collision detected* error. These aren't the only errors that can occur, but are the most common.

Users should be careful, when writing their code, to ensure that only one command bit is enabled at a time.

2) Robot_Command.location<X,Y,Z,yaw,pitch,roll> is not cleared, or contains one or more non-zero values
When the robot is commanded to move to a location Robot_Command.location_number, it is moved to the transformation (X,Y,Z,yaw,pitch,roll) values contained in the location_number specified, offset by Robot_Command.location<X,Y,Z,yaw,pitch,roll>. If the user desires an offset then this method can be used, but if no offset is intended or desired then Robot_Command.location should be cleared at the start of the program.

3) Changing motion qualifier bits while the move bit is turned on
Users should not make changes to speed, accel, decel, accel profile, settling, etc. while the move bit is enabled. It is also important not to change the location to move to while the move bit is enabled. As soon as a move is started it is OK to turn off the move bit and make changes. The move will complete as commanded, despite the move bit being disabled. Following this rule will prevent the read/write conflicts on the parameters you wish to change. If there are places in your code where parameters are changed while the move bit is on, especially changing the location, there is a chance that the new location can be written in error, resulting in one of the above mentioned errors.

4) Communication Speed between the PLC and the Adept Controller

Please see the attached screenshot.

In some cases, communication speed between the PLC and the Adept Controller has been proven to cause intermittent errors, the most common of which are *position out of range* or *obstacle collision detected*. Allowing auto-negotiation of port speed and duplex has been effective in alleviated this issue.
Allowing auto-negotiation of port speed and duplex
C20_PortConfig_condensed.JPG (62.28 KiB) Viewed 10400 times

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