schmersal PSC1 Series Installation Manual page 42

Installation manual
Cross comparison:
The inputs on the PSC1 modules are in principle designed internally as dual-channel. The
status of the input signals is continuously cross compared. Only with a high signal in both input
sub-systems is the high status of the input detected, if the signal level varies between the two
channels, the input is set to low status.
Dynamic test on the switching thresholds in the input sub-system:
The switching thresholds for the detection of the high level are tested cyclically with a high
rate. If the defined threshold is dropped below, a module alarm is triggered.
Dynamic test on the ability of the input sub-system to switch:
The ability of the input sub-system to switch to the low level is tested cyclically on all inputs
with the exception of DI5—DI8, with a high rate. If the defined threshold is dropped below, a
module alarm is triggered.
Diagnostic functions that can be activated by configuring parameters:
Cross-circuit test:
The PSC1 modules have pulse signal outputs on which a unique signature is superimposed.
On the usage of the cross-circuit test, the switching elements for the digital sensors / input
elements are supplied with an auxiliary voltage via the pulse signal outputs on the PSC1
module. In this way the signature is superimposed on the sensors' / input elements' high signal
level and checked by the PSC1 module. Short-circuits and cross-circuits to the high signal can
be detected by means of the signature check. With alternating usage of the pulse signals for
multiple contacts, parallel signal wires or with neighbouring terminal assignment, cross-circuits
between the related input signals are detected.
Sensors / input elements with 2-pole or multiple pole contacts without time monitoring:
The sensors/input elements can be assigned to several contacts. These therefore correspond
to at least 2-channel elements. A high level on the sensor/input element requires logical
connection in series of both contacts.
Example 1:
Input element with 2 normally closed contacts: High level if both contacts are closed
Example 2:
Input element with 1 normally closed contact and 1 normally open contact: High level if
normally open contact actuated and normally closed contact not actuated.
Sensors / input elements with 2-pole or multiple pole contacts with time monitoring:
Same check as before however with the additional monitoring of the input signals for
consistency of the defined level relationships within a time window of 0.5 s. If the levels differ
for a period > 0.5 s, a module alarm is triggered.
Start test:
Each time the safety module is switched on (=PSC1 module), the input element must be
tested in the low signal status direction (= defined safe status), e.g. actuation of the
emergency stop button or a door lock after system start.
Operative / organisational tests:
Beyond the diagnostic measures on the PSC1 modules stated above, cyclic testing can be
undertaken in the application. These tests can be used in the assessment of the DC.
Note:
HB-37350-810-01-38F-DE PSC1-C-10 Installation manual V1.1.docx Page 42 of 177
Version: 38F