Rockwell Automation 1771-VHSC , D17716.5.74 Very High S - Manual (Page 55)

Sample Programs B–2
Sample Program for PLC-5 Family Processors
MUL
MULTIPLY
SOURCE A
SOURCE B
N22:103
1000.000
DEST F23:0
3000.000
N21:0
13
1
VHSC BTR
Done Bit
This rung illustrates how to assemble the count MSD and LSD into one floating point word that can be used throughout the program. F23:0 is an
intermediate storage value and F23:1 contains the total count 0 value.
Total count = (MSD * 1000) + LSD, [F23:1 = (N22:103 * 1000) + N22:104]
N22:103 is count 0 MSD
F23:0 = (1000 * count 0)
721
ADD
ADD
SOURCE A
SOURCE B
F23:0
N22:104
DEST F23:1
3721.000
721
3000.000
This rung illustrates how to disassemable 1 floating point word into 2 integer words that are used as the MSD and LSD for preset count 0.
This same technique can be used for the rollover value as well as the output values.
MSD = TRUNCATE (FLTPNT/1000), [N22:13 = TRUNCATE (F23:2/1000)] while LSD = FLTPNT - (MSD*1000), [N22:14 = F23:2 - (N22:13*1000]
DIV
DIVIDE
SOURCE A
SOURCE B
F23:2
2789.000
DEST F23:3
2.789000
N21:5
13
1000.000
MOV
MOVE
SOURCE A
F23:3
DEST N24:0
2
2.789000
1
VHSC BTR
Done Bit
FLT POINT PRESET
STORE WORD
GRT
GREATER THAN
SOURCE A
N24:0
2
2.789000
SUB
SUBTRACT
SOURCE A
N24:0
DEST N24:0
2
2
INTEGER PRESET
STORE WORD
INTEGER PRESET
STORE WORD
SOURCE B F23:3 SOURCE B 1
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INTEGER PRESET
STORE WORD