CH 10: PLC Math Instructions

What condition sets the Zero (Z) bit in the ADD instruction?

• The result is negative.

• A carry is generated.

• The result is zero.

• The result does not fit in the destination location.

What does the Sign (S) bit indicate in the ADD instruction?

• The result is zero.

• A carry is generated.

• The result is negative.

• The result does not fit in the destination location.

What does the Overflow (O) bit indicate?

• Result is zero

• Result is negative

• Borrow is generated

• Result underflows

What is the purpose of the subtract instruction in the Allen-Bradley SLC 500 series PLC?

• To add two numbers

• To divide two numbers

• To subtract one number from another

• To multiply two numbers

What does "Dest" stand for in the subtract instruction block?

• The source of the first number

• The source of the second number

• The destination of the result

• The operation to be performed

How many operands does the Multiply (MUL) instruction have?

• One

• Two

• Three

• Four

In the MUL instruction, what can the sources be?

• Both must be numbers

• Both must be registers

• Both can be registers, or one can be a register and the other a number

• Both must be memory addresses

What must the destination be in a MUL instruction?

• A number

• A register

• A memory address

• A constant

What is the address for the Carry (C) bit in the table?

• S2:0/1

• S2:0/0

• S2:0/2

• S2:0/3

What condition sets the Overflow (O) bit according to the table?

• If the result is zero

• If the result is negative

• If the result overflows at the destination address

• Always cleared