User manual

Lean Managed Switch
7278_en_01 PHOENIX CONTACT 1-7
Figure 1-6 LMS supply
1.3.2 Alarm Contact
The switch has a floating alarm contact. Under normal conditions, the contact is closed
allowing current to flow. When power is lost, the contact opens, indicating an error.
Figure 1-7 Circuit diagram for the alarm contact
In the event of non-redundant power supply, the switch indicates a supply voltage failure
by opening the alarm contact. This error message can be prevented by connecting the
supply voltage to both terminals in parallel, as shown in Figure 1-6, or by deactivating
redundant power supply monitoring in web-based management.
US1
OUT
24 V DC
opt.
US1
OUT
24 V DC
opt.
12
72780003
R 1 R 2
6 7 8 4 0 0 1 5