Why does the position data field in Max, 1-D interactive not update ?

[DuncW]

I have correctly configured the motion board through max, and have correctly connected the linear motor and encoder with the MID 7654. When i move the motor by hand, the current trajectory data in 1-D interactive adjusts accordingly, suggesting i have correctly set the encoder resolution and sampling frequency in MAX. However when i go to perform a move ( 100000 counts = 10mm) the motor shoots past this position ( i understand that the PID characteristics need setting) what does not happen though is that when the axis is killed, the current trajectory field no longer responds to the manual adjusment of the motor, which it should!....... if i disconnect the encoder and then reconnect manual control is r
egained which seems bizarre !. then if i try and perform another move, sometimes it moves in the reverse direction to that specified and again once the axis is killed the current trajectory field no longer responds to manual adjusment................. I understand that erratic movement can be solved by correctly tuning the PID loop, however there seems to be a fundamental problem involving the feedback. I have checked the encoder, this works fine, NI have sent me a replacement control board but again the problem persists, could it be the power drive ?????, do you have any suggestions ???

[nestor-sg]

At first sight this looks like a discrepancy on the filter settings for the encoder. Could you please provide more details on which encoder you have and the frequency of the pulses coming into the MID? Do you have any other encoder? Have you tried other axes? If you already received a replacement board from NI, I would suggest you call back on the same service request so we can keep working directly on this issue with you.

When the reading fails you might want to check the encoder with an oscilloscope to see if its outputting clean 90 degrees out of phase TTL signals. Also, you might want to create a LabVIEW program (if you are programming in LV) that will check for the Encoder Position, not the "Read Position" VI, use the "Read Encoder Position" instead. Or in MAX whe
n this happens change to the Advanced tab page in the same 1D interactive and check the 'encoder' reading.

Good luck!

Nestor S.