ABB REL 356, Instruction Booklet

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LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY
Page 45 of 53
NORMALIZED FLOATING POINT NUMBER 41330 and 40331.
These subroutines require constants to be placed in specific registers as illustrated in the constant screen
windows listed at the end of this document. The constant values are used in allowing the subroutine to
calculate the numbers correctly. NOTE: these subroutines are required for three reasons:
•
The TPU, DPU and PCD use true integer numbers and the PLC only calculates numbers
using integer math for a range of 0000 to 9999 (Compact 984 limitation).
•
The COMPACT 984 PLC can perform mathematics calculations in IEEE Floating POINT,
thus a calculation must be made from the PLC numbers (0000 to 9999 or 00000000 to
99999999 [double precision integer]) to floating point numbers.
•
The MAGELIS MMI cannot display IEEE floating point numbers, so the results of the floating
point number must be changed to the integer format required by the MMI.
SEGMENT 7, the last segment in the program, is not set up in the ladder logic segment scheduler (as is
necessary for ladder logic subroutines). As illustrated in the ladder logic segments, 1 through 9 (Figures
91 through 96), the subroutine starts with a LAB instruction and ends at the RET command. The ladder
logic segments are listed with the constants required for operation.
Figure 91. Segment 7 Network 1:32 Bit Integer to Floating Point Number, Subroutine 1
Figure 92. Segment 7 Network 2: 32 Bit Integer to Floating Point Number, Subroutine 1