Emerson E2 Manuel D’Utilisation

NAME}:{UNIT NUMBER}:{BOARD NUM-
BER}:{POINT NUMBER}.”

Select Eng. Units   The Select Eng. Units field is 

where you may select how the ON and OFF states of 
this point are displayed and represented in E2’s setup 
fields and status screens. By default, digital inputs 
have ON-OFF engineering units, meaning when the 
input is ON or OFF, the input will be represented as 
“ON” or “OFF” in the system software.

Since the controller looks at only the actual state of 
the point when it uses the input for control purposes, 
it is not necessary to define engineering units for dig-
ital inputs. However, selecting units that are appro-
priate to the input’s function (such as BYP or 
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 used to detect when a 
push button (Momentary) switch has been pressed. 
When a button press is detected, the input will turn 
ON for one second, and then turn OFF. If the push 
button is pressed multiple times, the input will turn 
ON and back OFF for the same number of times that 
the button was pressed. The pushbutton input is 
designed to be connected to any application that has 
a BYPASS input. It may also be connected to the 
input of the Pulse Accumulator application to track 
the number of times the button has been pressed.

   If the pushbutton input is connected to an applica-

tion’s BYPASS input, a single button push will cause 
the application to go into bypass. If the push button is 
pressed three times within ten seconds, the applica-
tion will then cancel the bypass. An application must 
be in bypass mode for at least one minute before it 
may be cancelled. 

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.

The 8RO, 8IO, and MultiFlex combination I/O boards 

have relay outputs 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 deter-
mine if the connection will be open or closed during 
power failure. A fail-safe dip switch is used to determine 
connection status during network failure.

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).

N.C.       N.O.

N.C.       N.O.

RELAY IS

CLOSED

ON POWER

FAILURE

RELAY IS

OPEN ON

 POWER
FAILURE

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, 
and 8RO-FC, S3 on the 8IO, and S1 on the MultiFlex 
plug-in output board. Each switch corresponds to an out-
put 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