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6ć14, 3 multiply instruction 6.4.4 divide instruction – Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual User Manual

Page 136

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Data Manipulation Instructions

Chapter 6

6Ć14

The Multiply instruction tells the processor to multiply the two BCD
values stored at the Get instruction words. The result is then stored in two
data table words addressed by the Multiply instruction (Figure 6.15).

For ease of programming, the programmer should choose two consecutive
data table words to store the product. If the product is less than 6 digits,
leading zeros will appear in the product where there is no value. Although
this is not mandatory, any two unused data table words are acceptable.

Figure 6.15

Multiply Instruction

|ą|

12

( X )

503

111 052

| G |

123

130

| G |

061

131

Must be true to allow

arithmetic operation

( X )

007

051

The Divide instruction tells the processor to divide the first Get instruction
value by the second Get instruction value. The result is stored in two data
table words addressed by the Divide instruction (Figure 6.16). Usually two
consecutive data table word locations are chosen to store the quotient for
ease of programming.

The quotient is not rounded off and is always expressed as a decimal
number. The decimal point is automatically inserted between the two
Divide instruction values by the industrial terminal. Leading and trailing
zeros in the quotient are also entered automatically by the industrial
terminal.

Although division by 0 is undefined mathematically, the following results
are obtain with a PLC-2/30 PC processor when dividing by 0:

0

÷

0 = 001.000, 1 to 999

÷

0 = 999.999

This differs from the Mini-PLC-2 and the Mini-PLC-2/15 where 0

÷

0 =

999.999.

6.4.3
Multiply Instruction

6.4.4
Divide Instruction