in a daisy-chain configuration using 3-wire twisted,
shielded cable as shown in Figure 4.
Figure 4: FC bus terminal block wiring
When connecting the IOM to an SA bus, wire the bus
terminal block plugs on the expansion module and
other SA bus devices in a daisy-chain configuration
using 4-wire twisted, shielded cable as shown in
Figure 5: SA bus terminal block wiring
Note:
The SA PWR/SHLD terminal does not
supply 15 VDC. The SA PWR/SHLD terminal
is isolated and can be used to connect (daisy
chain) the 15 VDC power leads on the SA bus
(Figure 5) or the cable shields on the FC bus
(Figure 4). The SA bus supervisor supplies 15
VDC to devices on the SA bus requiring power.
Supply power terminal block
The 24 VAC supply power terminal block is a gray,
removable, 3-terminal plug that fits into a board-
mounted jack on the top right of the expansion
module.
Wire the 24 VAC supply power wires from the
transformer to the HOT and COM terminals on the
terminal plug as shown in Figure 6. The middle
terminal on the supply power terminal block is not
used.
Figure 6: 24 VAC supply power terminal block
wiring
Note:
The supply power wire colors may
be different on transformers from other
manufacturers. Refer to the transformer
manufacturer’s instructions and the project
installation drawings for wiring details.
Important:
Connect 24 VAC supply power to
the expansion module and all other network
devices so that transformer phasing is uniform
across the network devices. Powering network
devices with uniform 24 VAC supply power
phasing reduces noise, interference, and
ground loop problems. The expansion module
does not require an earth ground connection.
IOM2723 Input/Output Module Installation Guide
5
