Emerson E2 - Manual (Page 104)

9-10 • E2 RX/BX/CX I&O Manual 026-1610 Rev 13 14-SEP-2011
NO_BYP for inputs that initiate bypasses) will make
the input’s state easier to read and understand.
To choose an engineering unit, press
 (LOOK
UP) to select.
Push Button Mode? Digital inputs may be set up
as “push button” inputs by changing this field to
“YES”.
Push Button Mode is a method of interpreting a digi-
tal state that is used strictly for push buttons. When
used, a button press lasting longer than one second
will change the state of the input. In other words, if
the input is OFF, a button press will change it to ON,
and another button press will change it back to OFF,
etc.
Output This field displays the link between the input
and its application(s). You do not need to enter any-
thing in this field. You will be able to link applica-
tions to this point during the application setup
process.
9.2 The 8RO, 8ROe, 8IO,
and MultiFlex Outputs
The 8RO, 8ROe, 8IO, and MultiFlex have relay out-
puts that close when called to be ON and open when called
to be OFF. When an output point is closed (ON), the LED
directly above the output terminal glows red. These boards
use Form C contacts that determine if the connection will
be open or closed during power failure. A fail-safe dip
switch is used to determine connection status during net-
work failure.
9.2.1 Wiring Form C Contacts
Figure 9-8 shows how to wire the three-terminal Form
C contact.
One wire of the two-wire connection should always be
connected to the middle terminal. The second wire must
be connected to the N.C. terminal (if you want the relay to
be closed (ON) during power failure) or the N.O. terminal
(if you want the relay to be (OFF) during power failure).
9.2.2 MultiFlex Relay Outputs
The MultiFlex boards that have relay outputs (all mod-
els except the MultiFlex 16) each have eight relays that
energize and de-energize to control output loads.
When setting up an output on one of these relays, you
must make two important decisions:
1. Do you want an ON command from your control-
ler to mean “energize the relay” or “de-energize
the relay,” and
2. When the relay is de-energized, as is the case
when the 8RO or 8IO goes off-line or loses
power, do you want the contacts to be OPEN or
CLOSED?
Decision #1 is made by setting the fail-safe switch.
This is a bank of eight switches labeled S2 on the 8RO,
8ROe, and 8RO-FC, S3 on the 8IO, and S1 on the Multi-
Flex plug-in output board. Each switch corresponds to an
output on the board (switch #1 = output #1, etc.).
Decision #2 is made either by setting a fail-safe
jumper (for old-style 8ROs) or by wiring the load to
either the N.O. or N.C. terminals on the Form C contact
(all other output boards).
Table 9-3 shows how the fail-safe switch, jumpers,
and/or Form C contacts should be configured based on
how you want the output to perform during both normal
operation and during network/power loss.
9.2.3 Setting the Fail-Safe Dip
Switch
The fail-safe dip switch determines the sate of the relay
when communication is lost between the board and E2.
Figure 9-8 - Form C Contact Wiring
N.C. N.O. N.C. N.O.
RELAY IS
CLOSED
ON POWER
FAILURE
RELAY IS
OPEN ON
POWER
FAILURE
Controller
Command vs.
Contact State
Fail
State
Set
Switch
To:
Set
Jumper or
Wire Form
C
Contacts
To:
ON=CLOSED
OFF=OPEN ON UP N.C.
ON=CLOSED
OFF=OPEN OFF UP N.O.
ON=OPEN
OFF=CLOSED ON DOWN N.O.
ON=OPEN
OFF=CLOSED OFF DOWN N.C.
Table 9-3 - Output Board Fail-Safe and Switch Settings