It is strongly recommended that a normally closed, forced-guided monitoring contact of each FSD and MPCE be connected
in series with the EDM input (see
Generic Wiring Diagram—8-pin Receiver and Redundant FSDs
on page 51). If this is
done, proper operation will be verified. Monitoring FSD and MPCE contacts is one method of maintaining control reliability
(OSHA/ANSI) and Category 3 and 4 (ISO 13849-1).
If monitoring contacts are not available or do not meet the design requirement of being forced-guided (mechanically linked), it
is recommended you:
•
Replace the devices so that they are capable of being monitored; or
•
Incorporate the EDM function into the circuit as close to the MPCE as possible (for example, monitor the FSDs); and
•
Employ the use of well-tried, tested, and robust components, and generally accepted safety principles, including fault
exclusion, into the design and installation to either eliminate, or reduce to an acceptable (minimal) level of risk, the
possibility of undetected faults or failures that can result in the loss of the safety function.
The principle of fault exclusion allows the designer to design out the possibility of various failures and justify it through the
risk assessment process to meet the required level of safety performance, such as the requirements of Category 2, 3, or 4.
See ISO 13849-1/-2 for further information.
WARNING:
•
External Device Monitoring (EDM)
•
Creating a hazardous situation could result in serious injury or death.
•
If the system is configured for “no monitoring,” it is the user’s responsibility to ensure this does not
create a hazardous situation.
6.4.4 External Device Monitoring
EZ-SCREEN LS Basic Safety Light Curtain provides two possible EDM configurations: 1-channel monitoring and no
monitoring. Their functions are described below. The most common form of EDM is 1-channel monitoring; its primary
advantages is the simplicity of wiring. The installation must prevent short circuits across the N.C. monitoring contacts and to
secondary sources of power.
Figure 32. One-channel EDM status, with respect to safety output
Safety Output
Closed
Open
OFF
ON
EDM
Don’t Care
Don’t Care
Don’t Care
Don’t Care
250 ms
Max.
250 ms
Max.
250 ms
Max.
External Device Monitoring Wiring
If not connected previously, it is again strongly recommended that one normally closed, forced-guided monitoring contact of
each FSD and MPCE be wired as shown in the monitoring circuit (see
Generic Wiring Diagram—8-pin Receiver and IM-T-9A
External device monitoring (EDM) must be wired in one of two configurations described below.
One-Channel Monitoring:
This is a series connection of normally closed monitor contacts that are force-guided
(mechanically linked) from each device controlled by the EZ-SCREEN LS Basic. The monitor contacts must be closed before
the EZ-SCREEN LS Basic OSSDs can turn On. After the safety outputs (OSSDs) turn On, the status of the monitor contacts
are no longer monitored and may change state. However, the monitor contacts must be closed within 250 milliseconds of the
OSSD outputs going from On to Off.
Refer to
Generic Wiring Diagram—8-pin Receiver and IM-T-9A Interface Module
on page 52 for wiring. Connect the
monitor contacts b24 V DC and EDM (pin 3).
No Monitoring:
Use this configuration to perform the initial checkout; see
on page 37. If the
application does not require the EDM function, it is the user's responsibility to ensure that this configuration does not create a
hazardous situation.
To configure the EZ-SCREEN LS Basic Safety Light Curtain for no monitoring, connect EDM (Pin 3) to +24 V DC.
WARNING: Retrofit of 2-channel EDM Installations
—In existing installations using 2-channel external
device monitoring (default setting of EZ-SCREEN and EZ-SCREEN LP systems),
the parallel wiring of
the N.C. monitoring contacts must be rewired for the series connection used for 1-channel EDM
. If
the required wiring changes are not made, the device connected to pin 2 (Orn/Blk) will not be monitored
and could result in undetected faults and create an unsafe condition, which could result in serious bodily
injury or death.
If there are any questions concerning retrofit installations, contact Banner
Engineering.
EZ-SCREEN
®
LS Basic Safety Light Curtain
44
www.bannerengineering.com - Tel: + 1 888 373 6767
