[69owb]

Hi
I have two ac servo motors that I have to reverse the rotation of them. I've been told to just flip two of the wires that go to the motor what about the resolver do I need to flip any of those wires to. I know I have to switch A & A- And B & B- on the encoder. Thanks for the help

[MaxHeadRoom]

The resolver is usually a two phase detector, the third phase is derived from these two, so presumably you should be able to swop the two resolver phases and the first two lableled phases of the motor, i.e. if U,V,W this would be U&V.
To reverse the direction of an encoder, you only need to swop the A & /A signal.
In most controls, however, you do not need to go through this as it can all be done in software parameters.
Max.

[unterhaus]

depending on the system, there may be no way to do this with just hardware. Tell us more about your drive/motor.

[gridley51]

I don`t think it is as easy as reversing phases.The normal way to do it would be by changing the command to the drive.

[Al_The_Man]

I don`t think it is as easy as reversing phases.The normal way to do it would be by changing the command to the drive.

I agree that the best way is if the controller has the feature of reversal, but the method of reversing the two principle resolver phases and the first two motor phases should work in the majority of cases.
If commutation is satisfied then the controller does not know.
Similar reversal can be done on BLDC, as long as the commutation is in phase.
The encoder may have to be reversed as stated.
Al.

[69owb]

The drives are Allen Bradley 1391-des with 1326b servo motors. Camsoft Recommends to try to switch the wiring on the motors instead of changing it in the software they say it maybe can cause some issues in the software?
On the resolver would I flip S1 & S3 and then flip S2 & S4 or swap S1 & S3 with S2 & S4 ? Thanks

[Al_The_Man]

I would have dig out my AB manuals, but in the mean time there are Galil commands that will do this, I would think you should be able to achieve/access this through Camsoft.
Al.

[Al_The_Man]

. Camsoft Recommends to try to switch the wiring on the motors instead of changing it in the software they say it maybe can cause some issues in the software?

I am surprised that Camsoft recommend this solution, I believe what they mean is swap the two analogue conductors, you would also have to swop the A & /A.
Typically when you wire up a system 'to the book' the motor direction that gives for e.g. count up in the + may be the wrong direction, the MT command in the Galil will reverse the motor so that count up in the + is now reversed.
Check the Galil command manual for an explanation.
You can also reverse the encoder direction, but it should not be needed in this case.
Al.

[69owb]

I reversed it in the software by inserting a negative value in the gear setting it worked. The only thing I noticed was the limit switch's have to be set backwards in order for them to work right. I mite still try to switch the wires?

[Al_The_Man]

If you don't want to try the MT command, It may be preferable to swap the control loop rather than the motor connections.
i.e. The analogue and the encoder A, /A.
Al.