Siemens SIMATIC S7-400 Reference Manual page 46

Power supply modules
3.4 Operator controls and indicators
LEDs INTF, 5 VDC, 24 VDC
Table 3-2
INTF
5 VDC
24 VDC
LEDs BAF, BATTF
Power supply modules with a backup battery have the following indicators:
Table 3-3
BAF
BATTF
LEDs BAF, BATT1F, BATT2F
Power supply modules with two backup batteries have the following indicators:
Table 3-4
BAF
BATT1F
BATT2F
Backup voltage to the backplane bus
The backup voltage is either supplied by the backup battery or fed externally into the CPU or
receiver IM. In its normal state, the level of the backup voltage is between 2.7 V and 3.6 V.
The backup voltage is monitored at the lower limit. Violation of the lower limit is indicated by
the BAF LED and reported to the CPU.
46
LEDs INTF, 5 VDC, 24 VDC
LED Color
Red Lights up in the event of an internal fault
green Lights up as long as the 5 V voltage is within the tolerance limits
green Lights up as long as the 24 V voltage is within the tolerance limits
LEDs BAF, BATTF
LED Color
Red Lights up if the battery voltage on the backplane bus is too low and the
BATT.INDIC switch is at the BATT position
Yellow Lights up if the battery is empty, if the polarity is reversed, or if the battery
is missing, and the BATT.INDIC switch is at the BATT position
LEDs BAF, BATT1F, BATT2F
LED Color
Red Lights up if the battery voltage on the backplane bus is too low and the
BATT.INDIC switch is at the 1 BATT or 2 BATT position
Yellow Lights up if battery 1 is empty or if the polarity is reversed or if the battery
is missing, and the BATT.INDIC switch is at the 1 BATT or 2 BATT position
Yellow Lights up if the battery 2 is empty, if the polarity is reversed, or if the battery
is missing, and the BATT.INDIC switch is at the 2 BATT position
Meaning
Meaning
Meaning
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08