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19 BUILT-IN I/O FUNCTION
19.1 High-speed Counter Function
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■Reset
When comparison value 1 matches the current value of the set high-speed counter, the bit device specified as the output
destination device is reset.
Operation is the same as for the DHSCR instruction. For information on the DHSCR instruction, refer to MELSEC iQ-F
FX5 Programming Manual (Instructions, Standard Functions/Function Blocks).
■Self-reset
When comparison value 1 matches the current value of the set high-speed counter, the current value becomes the preset
value. When the preset value is set by self-reset, comparison processing is not performed.
Operation is the same as self-reset for the DHSCR instruction. For information on the DHSCR instruction, refer to
MELSEC iQ-F FX5 Programming Manual (Instructions, Standard Functions/Function Blocks).
■Zone Compare
Based on the current high-speed counter value, comparison value 1, and comparison value 3, one of the three output devices
from the head output device will be set. The rest are reset.
Operation is the same as for the DHSZ instruction. For information on zone comparison and DHSZ instruction, refer to
MELSEC iQ-F FX5 Programming Manual (Instructions, Standard Functions/Function Blocks).
Comparison start/stop for high-speed comparison table
High-speed comparison tables cannot execute comparison by setting the parameter alone.
The HIOEN instruction is required to start/stop the high-speed comparison table.
For the HIOEN instruction, refer to MELSEC iQ-F FX5 Programming Manual (Instructions, Standard Functions/Function
Blocks).
The DHIOEN instruction is required to start/stop high-speed counters as well when using a high-speed
comparison table.
Measurement is not conducted by starting the high-speed comparison table alone, and the high-speed
comparison table therefore does not operate.
Precautions
■Number of tables that can be set
Up to 4 tables can be set. Empty tables are not included in the number of tables.
■Processing order
High-speed comparison tables are processed in sequence starting from the first table.
■Operation start timing
High-speed comparison tables are updated during END processing. If started/stopped by the DHIOEN instruction, the table is
applied starting from the next scan. Caution must be exercised when controlling high-speed comparison tables using the
DHIOEN instruction several times within the same scan.
Ex.
Table operation is as follows when multiple DHIOEN instructions are executed within the same scan.
Tables 1, 2 and 4 are started at the 1st DHIOEN instruction.
Tables 3 and 5 are started, and 2 and 4 are stopped at the 2nd DHIOEN instruction.
Table 2 is started and 5 is stopped at the 3rd DHIOEN instruction.
Tables 1, 2 and 3 operate.
■Operation when using internal clock
Self-reset cannot be used for channels set to internal clock by pulse input mode.
Comparison value 1
Current value
Head output device
Comparison value 1
Current value
Comparison value 2
Head output device +1
Current value
Comparison value 2
Head output device +2
Set