Pins on ax1500

Hi, I purchased an ax1500 controller and was wondering what the 3 sets of pins on the top of it are for.

If you are referring to the 3 10-pin headers, they are:
<P style="MARGIN: 0px">1- Header for MCU programming and debug
<P style="MARGIN: 0px">2- Header for CPLD programming. Has I2S communication pins for encoder module, if installed.
<P style="MARGIN: 0px">3- Hardware configuration pins that should not be touched.

Will you offer an add-on encoder board for the ax1500 in the future?

<P style="MARGIN: 0px">The encoder module we sell for the AX2550 can be fitted on the AX1500.
<P style="MARGIN: 0px">
<P style="MARGIN: 0px">We do not advertise this capability because it makes little sense commercially given that this pushes the solution at practically the same price as the AX3500 which can handle more power.
<P style="MARGIN: 0px">
<P style="MARGIN: 0px">You may order the encoder module from the ordering page on the web site.