Emerson 810-3013, Installation And Operation Manual

Page: 14 / 36

8 • MultiFlex I/O Board Operator’s Guide 026-1704 Rev 6 06-APR-10
If there is a power LED next to the connec-
tor, your MultiFlex is a new-style MultiFlex --
refer to Section 2.3.3.1., New-Style MultiFlex
Combination I/O Boards (with Isolated Power
Supply)
for power wiring instructions.
If there is no power LED next to the connec-
tor, your MultiFlex is an old-style MultiFlex --
refer to Section 2.3.3.2., Old-Style MultiFlex
Combination I/O Boards (No Isolated Power
Supply)
for power wiring instructions.
2.3.3.1. New-Style MultiFlex Combina-
tion I/O Boards (with Isolated
Power Supply)
The new-style MultiFlex board can be con-
nected to any of the center-tapped transformers
mentioned in
Table 2-2 , provided the 0V termi-
nal of the board is connected to an Earth ground.
A center-tapped transformer may power
both center-tapped and non-center-tapped boards
at the same time, as long as
none of the non-
center-tapped MultiFlex boards are old-style
MultiFlex boards.
If an old-style MultiFlex
shares the same center-tapped transformer as a
device that uses the center tap, boards on the net-
work will be damaged.
Figure 2-6 shows how to
wire a non-center tapped device to a center-
tapped transformer.
In addition, the MultiFlex combination
boards can be powered by one of the 50VA or
75VA non-center-tapped transformers listed in
Table 2-1 on page 6.
Figure 2-7 shows how to
wire the transformers to the MultiFlex boards.
You may also tie one side of the secondary
(but not BOTH sides) or the center tap to an
earth ground, provided none of the boards pow-
ered by the same transformer are old-style Mul-
tiFlex boards (see
Section 2.3.3.2. ).
2.3.3.2. Old-Style MultiFlex Combination
I/O Boards (No Isolated Power
Supply)
Like the new-style MultiFlex board, the old-
style MultiFlex Combination I/O board can be
connected to any of the center-tapped transform-
ers mentioned in
Table 2-2 , provided you follow
the following three rules:
Rule 1: Ground the 0V terminal on the old-
style MultiFlex board to an Earth ground.
Do not connect the center tap of the trans-
former to the 0V terminal.
Figure 2-6 - Wiring Non-Center Tapped MultiFlex Boards to
Transformers With a Center Tap
Figure 2-7 - Non-Center-Tapped Transformer Wiring
All wire connections to earth ground should
be less than six (6) inches long and use a wire
gauge of at least 14AWG.