schmersal PROTECT-PSC, Instruction Manual

Page: 76 / 267

System description
3
Instruction Manual PROTECT-PSC
V 2.6R01 / 04.19
3
–44
3.8.2 Safety functions
Test pulses
The inputs are self-monitored by test pulses. Pulses of 450 to 500 µs are generat-
ed every 15 ms. The interrogation of the input channel is suspended for this brief
period.
An external switching process by the connected sensory analysis is taken into con-
sideration during this check.
The self-monotoring of external sensors, such as AOPDs, is not impaired by the
output of the test pulses.
Channel monitoring
In the case of 2-channel control the potentials of the individual channels are
checked for equality. External switching processes during the test are taken into
consideration.
Voltage monitoring
Every input module has an internal monitoring system for the connected 24 V DC
power supply, generating an error message in the case of an error.
Error messages
If errors occur during the above described measures or other internal/external
errors, these are read out by error messages. Every error message can be
generated by the A/B processor. The prefix (A/B) shows the processor from which
the message comes. The table below provides an excerpt from the possible error
messages of the input modules. A complete list of all error messages is provided in
Chapter7.3.3.
Test Error code Meaning
Supply sensors A/B 043-14
Supply voltage for the sensors too low or non-
existent
Test pulses A/B 043-21 Test pulses not detected
Channel monitor-
ing
A/B 043-22
Discrepancy of the input channels (in the
case of 2-channel control)
T
T
a
a
b
b
l
l
e
e
3
3
-
-
1
1
6
6
S
S
e
e
l
l
e
e
c
c
t
t
e
e
d
d
e
e
r
r
r
r
o
o
r
r
m
m
e
e
s
s
s
s
a
a
g
g
e
e
s
s
o
o
f
f
t
t
h
h
e
e
i
i
n
n
p
p
u
u
t
t
m
m
o
o
d
d
u
u
l
l
e
e
s
s
7.3.3 / 7-5