P/N 133487
25
Banner Engineering Corp.
•
Minneapolis, U .S .A .
www .bannerengineering .com • Tel: 763 .544 .3164
SC22-3 Safety Controller
Instruction Manual
System Installation
3.6 EDM, OSSD (Safety Output), and FSD Hookup
3.6.1 External Device Monitoring (EDM)
The Controller’s safety outputs can control external relays,
contactors, or other devices that have a set of normally closed
(N .C .) force-guided (mechanically linked) contacts that can be
used for monitoring the state of the machine power contacts . The
monitoring contacts are normally closed (N .C .) when the device
is turned OFF . This capability permits the Controller to detect if
the devices under load are responding to the safety output, or if
the N .O . contacts are possibly welded closed or stuck ON .
The EDM function provides a method to monitor these types of
faults and to ensure the functional integrity of a dual-channel
system, including the MPCEs and the FSDs .
An EDM input can be mapped to only one safety output .
The EDM inputs can be configured in three ways: one-channel,
two-channel, or no monitoring . One- and two-channel EDM are
used when the OSSD outputs directly control the de-energizing
of the MPCEs or external devices .
• One-Channel Monitoring: a series connection of closed
monitor contacts that are forced-guided (mechanically linked)
from each device controlled by the Controller . The monitor
contacts must be closed before the Controller outputs can be
reset (either manual or automatic) . After a reset is executed
and 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 .
• Two-Channel Monitoring: an independent connection of
closed monitor contacts that are forced-guided (mechanically
linked) from each device controlled by the Controller . Both
EDM inputs must be closed before the Controller can be reset
and the OSSDs can turn ON . While the OSSDs are ON, the
inputs may change state (either both open, or both closed) .
If the inputs remain in opposite states for more than 250
milliseconds, a lockout will occur .
• No Monitoring: If no monitoring is desired, simply do not
select either one-channel or the two-channel option . If the
Controller does not use the EDM function in category 3
or category 4 applications, the user must ensure that any
single failure or accumulation of failures of the external
devices does not result in a hazardous condition and a
successive machine cycle will be prevented.
CAUTION . . .
EDM Configuration
If the application does not require this function,
it is the user’s responsibility to ensure that this
does not create a hazardous situation .
NOTICE Regarding External Device Monitoring Hookup
It is strongly recommended that at least one normally
closed, forced-guided monitoring contact of each MPCE
or external device be wired in order to monitor the state of
the MPCEs (as shown in Figures 3-12 to 3-15) . If this is
done, proper operation of the MPCEs will be verified . MPCE
monitoring contacts must be used in order to maintain
control reliability .