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Comparison Instructions Section 5-18
Indirectly addressed DM word is non-existent. (Content of *DM word
is not BCD, or the DM area boundary has been exceeded.)
5-18 Comparison Instructions
5-18-1 COMPARE – CMP(20)
Limitations When comparing a value to the PV of a timer or counter, the value must be in
BCD.
Description When the execution condition is OFF, CMP(20) is not executed. When the
execution condition is ON, CMP(20) compares Cp1 and Cp2 and outputs the
result to the GR, EQ, and LE flags in the SR area.
Precautions Placing other instructions between CMP(20) and the operation which
accesses the EQ, LE, and GR flags may change the status of these flags. Be
sure to access them before the desired status is changed.
Flags ER: Indirectly addressed DM word is non-existent. (Content of *DM word
is not BCD, or the DM area boundary has been exceeded.)
EQ: ON if Cp1 equals Cp2.
LE: ON if Cp1 is less than Cp2.
GR: ON if Cp1 is greater than Cp2.
Example:
Saving CMP(20) Results
The following example shows how to save the comparison result immediately.
If the content of HR 09 is greater than that of 010, 10200 is turned ON; if the
two contents are equal, 10201 is turned ON; if content of HR 09 is less than
that of 010, 10202 is turned ON. In some applications, only one of the three
OUTs would be necessary, making the use of TR 0 unnecessary. With this
Cp1: First compare word
IR, SR, AR, DM, HR, TC, LR, #
Cp2: Second compare word
IR, SR, AR, DM, HR, TC, LR, #
Ladder Symbols Operand Data Areas
CMP(20)
Cp1
Cp2
Flag Address C1 < C2 C1 = C2 C1 > C2
GR 25505 OFF OFF ON
EQ 25506 OFF ON OFF
LE 25507 ON OFF OFF
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