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Power Entry Module (PEM)
39
R1.0, October 2018
8.8 PEM I²C-bus addresses
Geographic address pins (HA0, HA1) on the PEM Backplane connector
determine the I²C addresses of the devices. The I²C devices on the PEMs are
connected to channel 4 of the Master-Only I²C-bus of the Shelf Managers.
Table 8: PEM I²C-bus addresses
8.9 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 9: PEM PCA 9555 pin assignment
PEM Location
SEEPROM
LM75
PCA9555
PEM A (Right, view from rear)
0xa8/54
0x98/4c
0x48/24
PEM B (Left, view from rear)
0xaa/55
0x9a/4d
0x4a/25
PCA9555 I/O pin
Function
State
0.0
n.c.
0.1
Power Branch 1 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
0.2
n.c.
0.3
Power Branch 2 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
0.4
Power Branch 6 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
0.5
Power Branch 5 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
0.6
n.c.
0.7
Power Branch 3 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
1.0
n.c.
1.1
Power Branch 4 after the fuse
present
-48 V present = 0
-48 V absent = 1 (3.3V)
1.2
n.c.
1.3
Green LED
1=on
1.4
Hot Swap Push-button switch
1=not pushed, 0=pushed
1.5
Red LED
1=on
1.6
n.c.
1.7
Blue LED
1=on
