Technical data

LED Indicators
14-Slot Shelf
Chapter 2
101
Figure 2-14 PEM Block Diagram
PEM I/O Device
The PEM I/O device (PCA9555):
• Controls the status of the LEDs.
• Reads the status of the Hot-Swap push button.
• Reads the status of the -48 VDC inputs.
Table 2-17 PEM PCA Pin Assignments
PCA9555 I/O
Pin
Function State
0.0 Power input 2 Backplane connector
present
-48 V present = 0
-48 V absent = 1 (3.3V)