Banner EZ-SCREEN­ Safety Light Curtain Systems - Manual (Page 33)

3.7 Electrical Interface to the Guarded Machine (Permanent Hookup)
Make the electrical connections as described in Sections 3.7.1 to 3.7.4 as
required by each individual application.
Supply power and the external Reset switch should be previously connected by
this point. The EZ-SCREEN must also have been aligned and passed the Initial
Checkout, as described in Section 3.6. The final connections to be made are:
• OSSD outputs
• FSD interfacing
• MPCE/EDM connections
• Remote Test
3.7.1 OSSD Output Connections
Both the Output Signal Switching Device (OSSD) outputs must be connected to
the machine control so that the machine’s safety-related control system
interrupts the circuit or power to the Machine Primary Control Element(s)
(MPCE), resulting in a non-hazardous condition.
Final Switching Devices (FSDs) typically accomplish this when the OSSDs go to
an OFF state. See Figure 3-16.
Refer to the output specifications on page 13 and the Warning at left before
making OSSD output connections and interfacing the EZ-SCREEN System to the
machine.
3.7.2 FSD Interfacing Connections
FSDs (Final Switching Devices) can take many forms, though the most common
are captive contact, forced-guided relays or interface modules. The mechanical
linkage between the contacts allows the device to be monitored by the External
Device Monitoring circuit for certain failures.
Depending on the application, the use of FSDs can facilitate controlling voltage
and current that differs from the OSSD outputs of the EZ-SCREEN. FSDs can also
be used to control an additional number of hazards by creating multiple safety
stop circuits.
Safety Stop Circuits
A safety stop allows for an orderly cessation of motion for safeguarding
purposes, which results in a stop of motion and removal of power from the
MPCEs (assuming this does not create additional hazards). A Safety Stop Circuit
typically comprises a minimum of two normally open (N.O.) contacts from
captive contact, forced-guided relays, which are monitored (through External
Device Monitoring) to detect certain failures in order to prevent the loss of the
safety function. Such a circuit can be described as a “safe switching point.”
Typically, safety stop circuits are either 1-channel (single channel), which is a
series connection of at least two N.O. contacts; or 2-channel (dual channel),
which is a separate connection of two N.O. contacts. In either method, the safety
function relies on the use of redundant contacts to control a single hazard (if one
contact fails ON, the second contact will arrest the hazard and prevent the next
cycle from occurring).
page 33
Banner Engineering Corp. • Minneapolis, MN U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
Installation and Alignment
EZ-SCREEN Grid
Instruction Manual
WARNING . . .
OSSD Interfacing
To ensure proper
operation, the EZ-SCREEN OSSD
output parameters and machine
input parameters must be
considered when interfacing the EZ-
SCREEN solid-state OSSD outputs
to machine inputs.
Machine Control circuitry must be
designed so that the maximum load
resistance value is not exceeded
and that the maximum specified
OSSD OFF-state voltage does not
result in an ON condition.
Failure to properly interface the
OSSD outputs to the guarded
machine could result in serious
bodily injury or death.
!
WARNING . . .
Interfacing of both
OSSDs
Both of the OSSD (Output Signal
Switching Device) outputs must be
connected to the machine control
so that the machine’s safety-related
control system interrupts the circuit
to the machine primary control
element(s), resulting in a non-
hazardous condition.
Never wire an intermediate
device(s) in such a manner that
the safety function can be
suspended, overridden, or
defeated, unless accomplished in
a manner at the same or greater
degree of safety.
!