How to Display "-" on A320 V/S Digits

Hi all,

I have my A320 FCU interfaced with OC mastercard and displays and I am able to display speed, alt, headings, etc. My encoders all work smoothly and buttons operate correctly. My V/S seems to work ok when I adjust the encoder to a positive rate of ascent, but when I try and set it to a negative rate of descent, I don't get negative values, even though the range is set to -99 thru +99. (please don't scold me, I am STILL using IOCARDS software at this point, not SIOC). I also am interested in sending the "special" characters to the displays card to display the "-" sign when the V/S is set to a negative value, how do you acheive this?

Thanks,

Buddy