Allen-Bradley MicroLogix 1400 Instruction Manual page 185

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CTD and CTU Instructions Valid Addressing Modes and File Types
For definitions of the terms used in this table see Using the Instruction Descriptions on page 92.
Parameter
Counter
Preset
Accumulator
(1) Valid for Counter Files only.
CTU Instruction Counter Control and Status Bits, Counter Word 0
(Data File 5 is configured as a timer file for this example.)
Bit
bit 12 - C5:0/OV OV - overflow
indicator
bit 13 - C5:0/DN DN - done
indicator
bit 15 - C5:0/CU CU - count up
enable
retained until cleared by a reset (RES) instruction that has the same
address as the counter.
TIP
Addressing Modes and File Types can be used as shown in the following
table:
(1)
Data Files
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Using Counter File Control and Status Bits
Like the accumulated value, the counter status bits are also retentive until
reset, as described below.
Is Set When:
the accumulated value wraps from
+32,767...-32,768 and continues to count
up
≥
accumulated value preset value
rung state is true
The counter continues to count when the accumulator is greater than the
CTU preset and when the accumulator is less than the CTD preset.
Function Files
And Remains Set Until One of the Following
Occurs:
a RES instruction with the same address as the CTU
instruction is enabled
• accumulated value < preset value or,
• a RES instruction with the same address as the CTU
instruction is enabled
• rung state is false
• a RES instruction with the same address as the CTU
instruction is enabled
Timer and Counter Instructions
Address
Address Level
Mode
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Publication 1766-RM001A-EN-P - October 2008
183
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