# Illegal position data with Mitsubishi Melfa RV-2F-Q robotic arm

I have a project where I have to move a Mitsubishi Melfa RV-2F-Q robot to a position/orientation from an external source, so there are no pre-defined points available.

The problem I keep running into is that even if I give it a reachable position (within operating range), or even a position that is almost the same as its current one, it fails to move there with the error:

L2802 Illegal position data (dstn)

What causes this and how do I avoid it?

## 1 Answer

Robots use many coordinate system and for each position you transmit to the robot, it has to be specified in which coordinate system is it defined. If you do not define it explicitly, an implicit definition is used, which may not correspont to the one in which the current postition is defined. So what you think is exaclty near the robot, may be actually out of the operating range.

A simple case is when you give the robots coordinates in its base frame, but it expects realtive coordinates (in tool frame). If the current pose in the base frame is [1, 0, 0, 0, 0, 0] any you try to reach the coordinates [1.1, 0, 0, 0, 0, 0], in realtive coordinates you should transmit [0.1, 0, 0, 0, 0, 0]. The coordinates [ 1.1, 0, 0, 0, 0, 0] realative to the tool frame are be most probably out of the workspace. (vice versa is also true)

Also check the allowed operation envelope. An incorrect setup of the operation envelope could also cause similar problems.