Atest Gaz Alpa EcoDet XT, Руководство пользователя

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6.3 Bus layout with a closed alarm loop
That layout differs from the previous one in one aspect, namely the far end of the power supply line and the
communication bus is looped back to the control unit that is provided with a dedicated port for test of the
communication loop (e.g. the Alpa MOD LED1 Control Unit). Such a solution improves power supply
conditions for gas detectors and improve the system reliability since immunity to failures (breaks) of the
communication bus is reduced. The layout makes it also possible to test continuity of the loop and verify
reliability of the system operation by simulation of an alarm signal at the TEST LOOP port of the control unit,
which facilitates scheduled tests of the system operability.
Figure 6: Connection with the Alpa MOD LED1 Control Unit into a closed bus system
The detailed schematic diagram for such a layout is provided in Appendix [3].
6.4 Other possible layouts of gas detection systems
Modifications of the foregoing solutions are possible to set up mixed layouts. For instance, several network
fragments with the bus layout can be connected to individual inputs of a control unit. If so, a mixed system
is set up with several independent zones but only one control unit is necessary. However one has to keep in
mind that such a solution may need installation of additional power supply units to supply specific
fragments of the system since sufficient consumption of electric current must be covered.
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User Manual: POD-043-ENG R03