Sensor systems 2 AS-Interface

Issue date 2004-11-19 - Catalogue AS-Interface 2004/2005
4.3 Safety monitor
AS-Interface - Safety at Work
The safety monitor has the task of monitoring the safe slaves to ensure their
fault-free function during normal operation and maintaining a safe condition
via positive-action relays in the event of a fault. To this end the safety monitor
"listens to" the AS-Interface communication. All the slaves are called up
by the master on every cycle. In addition to the input status of each of the
connected sensors/contacts the signal response of the safe slaves contains
a 4-bit safety code, which is continuously varied on each query according to
a stored, fixed algorithm. If this 4-bit code is not modified as expected a fault
condition is detected and the system is safely shut down. In this case the
code "0000" is transmitted and results in a switch-off in no more than
40 msec (max. cycle time including repetition and processing time). The
safety monitor requires no address, but it does allow an address to be assigned
for communication with the master, so that all diagnostic information
is also available to the master.
The configuration of the initiation circuits is carried out by the ASIMON configuration
software, which enables the logic operations to be defined. Either
1 or 2 safe outputs are available to the safety monitor to facilitate the safe
shut down. The following functions can be configured in the safety monitor
in stop category 0 and stop category 1:
EMERGENCY-STOP function
Two-hand operation
Door locking
Protection checks
Restart inhibit
The AS-Interface connection localises the position at which the EMERGEN-
CY-STOP is activated. In addition, further information on the type of fault
can be transferred, so that down time can be minimised.
The user can also choose betwee the Standard Safety Monitor and the "Enhanced"
Safety Monitor. The difference between these two monitors is indicated
in the following table:
Technical features Standard Enhanced
Number of logic modules no AND,
only 2 x OR
6 x AND,
6 x OR,
1 R/S Flip-Flop
Number of configuration modules 32 48
Timer function No Yes
Contact debounce function No Yes
Deactivation of function modules No Yes
NOP (No operation) function as space holder1 No Yes
1
Due to timing reasons, at least 5 addresses must be given in the monitor.
The NOP function allows virtual addresses to be used.
The state of the power-off circuit is displayed on the monitor using LEDs:
red LED on: switched off
yellow LED on: ready to restart after release
green LED on: running application
Subject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
Pepperl+Fuchs Group Tel.: Germany +49 621 776-0 USA +1 330 4253555 Singapore +65 67799091 Internet http://www.pepperl-fuchs.com
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Masters and
Gateways
Power Supplies,
Extender, Repeaters
Safety at work
I/O Modules
Control cabinet
I/O Modules
Field application
Analogue modules
Other modules
Inductive sensors
Photoelectric
sensors
Rotary encoders
Accessories