Output Fail-Safe Dip Switches; Relay Output Ratings And Fuse Protection - Emerson MultiFlex RTU Installation And Operation Manual

4.2.4. Output Fail-Safe Dip
Switches
When a controller calls for a MultiFlex relay
output to be ON, it sends a command to the
MultiFlex to turn the output to the ON state
(signified by the output LED being ON). The
behavior of the relay when it is ON is
determined by the position of the fail-safe
switch. The fail-safe switches for the outputs are
on a switch bank at the bottom right corner the
plug-in output module. Each switch corresponds
to an output on the board (switch #1 = output #1,
etc.).
State of Normally Closed (N.C.) Contacts on
Ligh
Fail-safe
t is
Switch
ON
Up (ON) Closed
Down (OFF) Open
Table 4-5 - Output Board Fail-Safe and Switch Settings when Contact is Wired Normally Closed (N.C.)
State of Normally Open (N.O.) Contacts on
Ligh
Fail-safe
t is
Switch
ON
Up (ON) Open
Down (OFF) Closed
Table 4-6 - Output Board Fail-Safe and Switch Settings when Contact is Wired Normally Closed (N.O.)
4.2.5. Relay Output Ratings and Fuse
Protection
Each relay output on the MultiFlex Combination
I/O boards is rated for up to 240 VAC with a
maximum current of 2A.
Each relay is fused with a 2A fast-blow 5mm x
20mm fuse, Bussman GMA-2 or equivalent.
The Outputs
MultiFlex Relay Points
Ligh Loss of
t is Commu-
OFF nication
Open Closed
Closed Closed
MultiFlex Relay Points
Ligh Loss of
t is Commu-
OFF nication
Closed Open
Open Open
Table 4-5 and Table 4-6 show how the fail-safe
switch and Form C contacts should be
configured based on how you want the output to
perform during both normal operation and
during network/power loss.
Note: There are not many cases where you
would want a relay to be OPEN when called to
be ON. For most applications, you will want to
set the fail-safe switch to UP so that an ON
command from the controller will close the relay.
Loss of
Power
Closed
Closed
Loss of
Power
Open
Open
RTU Input and Output Setup • 15