Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 154)

Chapter 9
Using Comparison Instructions
9–3
Function Codes
Each comparison instruction has three function codes associated with it. The
code that you use correlates to the way the instruction is used on the rung, as
described in the table below.
If the instruction is then use the code for
the first instruction on the rung or block LD <instruction>
in series with another instruction AND <instruction>
in parallel with another instruction OR <instruction>
Since there are three codes for each instruction, you do not press a separate
key to enter the action the instruction should take. (i.e., You do not press the
LD instruction key and then enter a function code for EQU to get LD EQU.)
Using Indexed Word Addresses
When using comparison instructions, you have the option of using indexed
word addresses for instruction parameters specifying word addresses.
Indexed addressing is discussed in chapter 6.
Use the EQU instruction to test whether two values are equal. If source A
and source B are equal, the instruction is logically true. If these values are
not equal, the instruction is logically false.
Source A must be a word address. Source B can be either a constant or word
address. Negative integers are stored in two’s complement form.
Entering the Instruction
HHP Display Mnemonic
Function
Code
Use This Instruction When the Input:
EQU LD EQU 50 appears first on a rung or block
EQU AND EQU 51
is placed in series with any previous input
instruction in the current rung or block
EQU OR EQU 52
is placed in parallel with any previous in-
put instruction in the current rung or block
You enter the instruction from within the program monitor functional area.
The example that follows shows how to enter the LD EQU instruction. Use
the same procedure to enter the other EQU instructions, only substitute the
function code with one from the table above.
21.92
EQU
EQUAL
Source A
N7:11
0
Source B 100
Execution Times (
µ
sec) when:
Ladder representation:
False
21.52
True
6.60 LD EQU
7.00 AND EQU
21.92 7.00 OR EQU
Equal (EQU)