Test Input; Fail-Safe Semiconductor Outputs - Leuze lumiflex Compact C14 Series Connecting And Operating Instructions

3.5.4

Test Input

The COMPACT is equipped as AOPD Type 4 with a permanent self-monitoring function, which
automatically detects faults in the system as well as cross-circuits and short-circuits to the output
cables. An external signal is not required for this. In order to test connected circuits for follower pro-
tection devices, an external control (e.g. combination of protection devices) can switch off the OSSD
outputs by means of a test signal and thereby test the drop in the switching devices (refer to Chapter
5.4 in this context). If this test function is not required, then the connecting terminal 3-4 of the trans-
mitted shall be bridged by a jumper (already set by factory).
3.6

Fail-safe Semiconductor Outputs

Both switching outputs OSSD1 and OSSD2 of the receiver are active-monitored pnp semiconductor
outputs for switching earthed loads up to 0.3 A. The outputs are HIGH-active and carry the voltage
U = U
OSSD supply
interrupted protection zone.
In order to monitor the safe function of the outputs, they are switched OFF cyclically every 140 µs
(Channel 1) and every 80 µs (Channel 2). A cross-circuit between the output cables 3 and 4 of the
COMPACT receiver is detected immediately after signal changing of the outputs from OFF to ON
by the self monitoring system. Then both outputs are switching to OFF as long as the cross-circuit
exists. In case of a short-circuit of an output to + 24 V the other OSSD output will be switched to
OFF as long as the short-circuit exists. Short-circuits to +24 V and 0 V are well as cross-circuits
between OSSD1 and OSSD2 are indicated and do not lead to a destruction of the outputs (refer to
Chapter 5.2 for circuits).
The semiconductor outputs are equipped with a fast de-energising function. Radio interference
suppression circuits are not necessary. The fast de-energising function reduces the release time to
a fraction in comparison with the conventional actuation of relays with recovery diodes. In total, this
leads to a shorter reaction time of the protective fixture.
Leuze lumiflex
- 2,7 V for an uninterrupted protection zone. U amounts to max. 2 V for an
OSSD
COMPACT 57