The MODF number shows which slots are reporting faults. Five digits allow complete coding of the 17 slots as follows:
Module slots #1 to #4 are represented by the lowest digit (0 0 0 0 X)
Modules slots #5 to #8 by the second lowest digit (0 0 0 X 0)
Modules slots #9 to #12 by the third lowest digit (0 0 X 00)
Modules slots #13 to #16 by the fourth lowest digit (0 X 000)
Module slot #17 only is represented by the fifth lowest digit (X 0000)
Each of the module slots is represented by a bit in a hexadecimal number, and each bit is either on or off (off = 0 = no
fault, on = 1 = fault).
The lower four hexadecimal numbers represent four modules each while the fifth hexadecimal number represents only
module slot 17. Therefore the fifth digit can only be a 1 or a 0 depending upon the fault condition of module in slot 17
only.
The four lower hexadecimal numbers each show the conditions of four module slot positions as follows:
0 = no faults in any of the four module slots represented in that group of four slots
1 = fault in the lowest slot number in that digits group of four slots
2 = fault in the second lowest slot number in that digits group of four slots
4 = fault in the third lowest slot number in that digits group of four slots
8 = fault in the highest slot number in that digits group of four slots
The hexadecimal number in each digit represents the sum of the four fault bits for that group, i.e., if slots #2 and #4 have
faults, the lowest digit will show an A which represents the sum of 8 and 2 in hexadecimal. If all four slots in a group
have faults then the digit will show an F (1 + 2 + 4 + 8 = 15 = F).
If the hexadecimal number shown is 1 0 0 F 0, modules in slots #5 through #8 and module in slot #17 are giving fault
indications.
Some examples of fault conditions follow:
SLOT NUMBERS
17
13-16
9-12 5-8 1-4
00000Nofaultsdetected
01060Faultsdetectedinslots#13,#6,and#7(Firstslotrepresentedbydigitfourand
second and third slots represented by digit 2)
1 0 F 0 0 Fault detected in slot #17 and in slots #9, #10, #11, & #12
00220Faultsdetectedinslots#10and#6
0 C 0 0 0 Faults detected in slots #15 and #16 (8 +4 = 12 = C)
1 F F F F Faults detected in all 17 slots
Decimal# 123456789101112131415
Hexadecimal# 123456789ABCDEF
Table 6-1. MODF Hexadecimal Coding vs Slot Faults
6-4 888-2365-001
WARNING: Disconnect primary power prior to servicing.
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