EUCHNER Safety Basic Monitor - Manual (Page 45)

Subject to reasonable modifications due to technical advances Id.-No.: 114013 Issue date: 14.11.2011 EUCHNER GmbH + Co. KG 45
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Safety Basic Monitor
Safety Requirements
8. Safety Requirements
8.1 Safety consideration for selecting OSSD/potential-free contacts
Potential-free contacts are cross-circuit monitored by the module. OSSD outputs
test themselves and only require that the module tolerate the test pulses.
If the module is incorrectly configured so that OSSDs are connected but potential-
free contacts are configured, a cross-circuit is detected, since the test pulses
which the module sends out on S82 and S62 do not correlate with the test pulses
on S81 and S61. The error is thus detected.
If the module is incorrect configured so that potential-free contacts are connected
by OSSDs are configured, Contact S81 / S82 is never seen as turned on, since
S82 is not turned on as a supply pin for the OSSD module. The error is thus de-
tected. The same applies by analogy to Contact S61 / S62.
8.2 Recommendation for improved availability of the function
The switching contacts should be turned off for at least 41 ms, since the safety
monitor (depending on the set monitoring component) must recognize the INPUT
OFF for a minimum number of AS-i telegrams. IF the minimum off time of 41 ms
(depending on the number of slaves on the AS-i bus and the set monitoring com-
ponent) is maintained, correct recognition of the input state is assured. Non-ob-
servance of this time may limit the availability of the AS-i Safety Monitor as fol-
lows:
• A setting of TWO-CHANNEL POSITIVE OPENING can cause the Safety
Monitor to go into the error state; to eliminate the error state, the supply volt-
age for the Safety Monitor must be disconnected.
• A setting of TWO-CHANNEL DEPENDENT means the Safety Monitor allows
release only after a sufficient off-time; the release can be achieved if the
switching contacts are turned off for at least 41 ms .