I am upgrading an older 3 axis Bridgeport CNC mill with a Galil 1842 motion card and the ICM 2900 interconnect. I am using the existing DC brush type servo motors and drives. As soon as the drives are energized/enabled the motors take off under power regardless if the control software is on or off. There is encoder and tachometer feedback that was processed through the old control. As it is wired now the only feedback that goes through the new control (Camsoft) is the encoder. Do the tach signals need to get wired through the ICM? When the control is on the motors respond the same and the red led on the motion card turns on immediately. I have not yet checked the motion command wiring because the card faults out. I just don't understand what is driving the motors without a command signal. Any ideas. Thanks, Dan
Galil_AndyH on 01/13/2009 - 15:43
The first thing to always check with a runaway condition is reverse polarity of the feedback from the motor. If the encoder is single ended (Only A+ B+, no A- or B-), then swap A+ and B+ to the ICM. If the encoder is differential (A+/- and B+/-), then swap A+ and A- to the ICM.
If this doesn't make any difference, make sure you are getting encoder feedback. Disable the drives and move the motors by hand, check the position of the encoders with the TP command. If TP is not changing, then the controller is not receiving the encoder signal.
The other thing you should do is install the MO jumper on the controller. This will cause the controller to power-up in a motor off state. If your amplifier enable signals are wired correctly, then you should be able to energize the drives with the controller in a motor off state.
The controller cannot take a tachometer input.