SCOM-100, User guide 15
SCOM-100 has two ways to provide power supply for the
I/O expansion units.
Bridge Vcc to Vex on the main SCOM-100 unit to power
a limited number of I/O expansion units (up to 4), as
shown below. (Power is then wired through the 6th pin on
to the modular I/O expansion connector).
If the number of expansion modules is more than 4, an
external power supply source must be connected to the
power connector screw terminals of each expansion
module, as shown below, and the Vcc to Vex on the main
SCOM-100 unit must not be bridged.