H-S81-HS Installation & Operation Manual — P/N LS10114-000HI-E:A 2/24/2015 21
Safety-Related Modules in the H-S81-HS System General Description
1.5.2 Digital Input Modules
Safety-related digital input modules feature a circuit allowing to simulate the opening and closing
of each channel. During operation, channels are cyclically tested. It a redundant module exists, the
control panel keeps operating and gathering data from this module, guaranteeing maximum system
availability. The broken module can be replaced without the need of switching off the system.
1.5.3 4-20mA Input Modules
4-20mA safety-related input modules feature two separated measuring circuits per input channel.
The two measured current values are, hence, compared between them and in case of difference
between the two values the channel is set in failure condition. It a redundant module exists, the con-
trol panel keeps operating and gathering data from this module, guaranteeing maximum system
availability. The broken module can be replaced without the need of switching off the system.
1.5.4 Output Modules
Safety-related output modules feature two control drivers connected in series. During operation, the
output channels are cyclically tested by reversal of output status for some hundreds of microsec-
onds. In case of difference between channel set status and the measured one, the whole module is
excluded from operation and its outputs are put in safety condition. (Shut-down) If a redundant
module exists, the control panel keeps operating and gathering data from this module, guaranteeing
maximum system availability. The broken module can be replaced without the need of switching
off the system.
Figure 1.5 Digital Input Test
Figure 1.6 Analog Input Test
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