On the VMA1610/1620 models, when the 128 bit switch on the address DIP switch is turned ON (to enable wireless operation), the FC and SA bus are swapped internally. All connections that were SA bus (RJ-12 and terminal blocks) are now FC bus connections. The terminal block connections marked for the FC bus are now connected internally to the SA bus.
If you have an installation that calls for a wired IOM connected to the SA Bus of a wireless-enabled VMA1610/1620 field controller, connect the IOM to the FC Bus Terminals (which are really the SA Bus terminals on a VMA1610/1620 in wireless mode) as indicated in #d7e987__fig_gtd_q12_dgb and Figure 4.
The VMA1615/1630 controller have RJ-12 connectors on the FC bus and SA bus. These controllers do not require port swapping when in wireless mode.