Autoscan Doesn't Find my Sub-Controllers

Controllers:
A LED - Task (heart beat)        B LED - Comm to PC          C LED - Comm to Subs

Sub-Controllers:
SCPs   A LED - Task (heart beat)       B LED -  Comm on Sub Bus
APCs  1  LED - Task (heart beat)      2  LED -  Comm on Sub Bus

1. Remove power from APC/SCP sub-board(s), flip the dipswitches back and forth to insure proper seating.  Dipswitches 6 & 7 should be switched ON for a baud rate of 38400.  
2. Make sure addressing is correct (dipswitches) and there are no duplications.

3. Make sure the appropriate wire is being used, Twisted Pair? Shield? Standard wire with no twist will not work especially over a distance due to RF interference.

4. What is the distance of the RS-485 bus? 4000 feet is industry max.

5. End-of-Line Jumper should only be terminated a last Sub-Controller on a long distance run for the Comm Bus.  

6. T-tapping into a Comm Bus and adding Sub-Controller to that leg may not be seen on Comm Bus.  No spider webs for Comm Bus, must be a straight continuous line in and out of sub-controllers.