KEYENCE GL-RHG Series - Manual (Page 29)

2-5 GL-RHG-M-NO2-E
Fu
nct
ion
s and
Feat
ures
2
2-3
OSSD
The OSSD is a safety-related control output. It connects to an external device (load), such as an FSD or
MPCE. The GL-RHG generates self-diagnosis signals on its internal control circuit to perform diagnostics
on the output circuit (OSSD). These signals periodically force the OSSD into a temporary OFF state when
no interruption exists in the protective zone.
If the internal control circuit receives a feed-back signal (OFF signal) based on the self-diagnosis, the
GL-RHG determines that its output circuit is operating normally. If this OFF signal is not returned to the
internal control circuit, the GL-RHG determines that there is a problem in its output circuit or wiring and
goes to the error condition.
Point The devices connected to the OSSD, such as safety relay or contactor, should not respond to
these temporary, self-diagnostic OFF-signals.
 Time chart
T1: ON to OFF Response time "Response time (OSSD)" (page 7-5)
T2: OFF to ON Response time "Response time (OSSD)" (page 7-5)
DANGER
For the wiring between the GL-RHG and the safety-related part of a machine control system,
both OSSD 1 and OSSD 2 must always be wired to a safety-related part of the machine
control system in order to ensure safety. If only one OSSD is wired to the safety-related part
of a machine control system, it results in significant harm to the machine operators,
including serious injury or death, if OSSD malfunction were to occur.
OSSD 1
ON
640 to 940ms
A
OFF
A : 50 to 250s
B : 53 to 79ms
OSSD 2
ON
OFF
B
GL-R
OSSD
Clear
ON
OFF
Approx. 3 sec.
Start-up
Blocked
T1 T2