You need to do the following before using the Johnson Controls N2 Bus Controller Communications option:
Acquire MMCVT1010 from Johnson Control.
Acquire or fabricate Custom Cable as shown in Figure 11.
Select RS232 Port on NT Host Computer.
Assemble as shown in Figure 12.
Verify that green power indicator in MMCVT1010 is on.
Use n2_diag probe command to verify communication.
About Johnson Controls N2 Bus Communications.