ICS-7-OEM Instruction Manual
02058-53-000
Page 22 of 29
Issue 3 19 January 2021
8
Mismatch Detector
The ICS-7-OEM trips out and disables the laser when either of its two safety circuits opens. If all the
door interlock and emergency stop switches have two contacts, one in each safety loop, then it is
normal for both safety circuits to open more or less simultaneously.
When the ICS-7-OEM Safety Circuit Mismatch Detection is enabled, if the second safety circuit does
not open within a short time of the first (typically around 1 second), a mismatch is triggered and the
Fault light illuminates on the front panel. It is then not possible to arm the system.
The ICS-7-OEM can also detect a mismatch between its two ‘Output Monitor’ circuits. If for example
these terminals are being used to monitor a pair of power contactors, should one of the contactors
become welded ‘on’ a mismatch will be indicated and the system will be locked out until the
contactor is repaired and the ICS-7-OEM is reset.
Safety Circuit Mismatch Detection can only be used if all inputs to the ICS-7-OEM are dual channel.
This includes all the door contacts and emergency stop buttons. If any input only operates one
channel, then a mismatch will inevitably occur and the mismatch detector will be triggered. In the
event that it is not possible for all of the inputs to be dual channel, the mismatch detector must be
disabled as described later in this section. Note that the use of a single channel safety contact and
the disabling of the mismatch detector will reduce the achievable safety performance level of the
system.
8.1 Configurable Options for Safety Circuit Mismatch Events
Mismatch Event Behaviour
In the event of a mismatch being detected either of the following two actions are available
depending on the option switch settings:
a) Lock out, preventing further use, unless the system is reset by switching it off and on again;
b) Lock out, preventing further use, unless the system is attended to by a qualified technician.
Option a) is suitable for mission-critical applications where the inability to use the laser would be
costly or inconvenient. Having detected and indicated that there is a fault it allows the system to be
reset to operate on the one good safety circuit provided the faulty circuit has been closed. The need
to manually reset the system before it can be used provides a clear indication to operators that
there is a problem that needs to be addressed at the earliest opportunity and that other risk
limitation steps may be required in the interim. An example might be to secure the affected door out
of use until it can be repaired.
Option b) is the lowest risk option, as once a safety circuit fault has been detected the system cannot
be used. The ICS-7-OEM can only be reset by opening the cabinet in which it is mounted and
operating the Fault Reset button. Procedures should indicate that this is only carried out by suitably
trained technicians once the fault has been repaired.
By default, the mismatch detector is factory set to be enabled in option ‘a’ above.
