We have a network of 18 smx-6 units for a few years now, and we are very happy with it. When ever we have to replace a unit it is very difficult to find a new one. We decide to purchase USM810 mixers to replace, little by little, each smx-6 that may need replaced. I am trying to configured the first 810 in my computer and after I connected it via RS232 the loop is checked but the unit is not found. I am familiar with the old msx-6 units but not with this model. Could some one tell me what I am doing wrong, or what I am missing?. Thanks in advance.