Eurotherm 590 DC Drive setup

Hi...
We have used Eurotherm 545 series DC Drive and we replace using 590 series DC Drive. The application using for unwind application. The existing is using analog tacho as speed feedback, speed ref from S5 PLC. We have "feedback speed alarm" problem since we change to 590 series and run the machine.
How to solve this problem?
Thank you
Edward

More information would be helpful

What exactly is the fault you describe, is this on the drive or on the siemens ?

Which 590 is it exactly and what wiring did you swop over from the 545 to the 590 ie 545 pins - 590 terminals ?

Did you tune the drive ?

Did you set the drive up correctly ie ramps, current limit etc etc ?

edit:
After looking at my manual for a 590 digital (not an analogue or +) which i presume is what you have your error from the manual is as follows

This alarm means that the drive is not receiving a signal back from the tach in the form it expects to see. It may be scaled wrong, the polarity may be backward, or it could even be an AC tach and the drive is looking for a DC tach.

You need to read the instruction manual carefully to get these to match up. Usually, the tach has its own nameplate which gives you its output.