Mitsubishi Electronics FX5 ユーザーズマニュアル

19  BUILT-IN I/O FUNCTION

19.1  High-speed Counter Function

This section describes the precautions when using high-speed counters.

This section describes the common precautions when using high-speed comparison tables and multi-point output comparison 
tables with the high-speed counter instructions (DHSCS, DHSCR, DHSZ instructions) or parameters. For the individual 
precautions on high-speed counter instructions, refer to MELSEC iQ-F FX5 Programming Manual (Instructions, Standard 
Functions/Function Blocks).

■High-speed counter devices

The current values for high-speed counters are checked with special registers for each channel.
To start or stop counting of the high-speed counters, use the HIOEN instruction or the SPD instruction.
 • High-speed counter start/stop conditions

*1 Can be stopped when counting was started with the SPD instruction.
*2 Can be stopped when the high-speed comparison table is not set with parameters.

■Precautions for the counting operation when the current value is changed

For the high-speed counter instructions, high-speed comparison tables, and multi-point output high-speed comparison tables, 
comparison processing is performed when the current value of the high-speed counter has changed due to pulse input. When 
the preset input comparison function is also enabled, comparison processing is also performed when the preset is executed.
However, please note that the comparison processing is not performed when the current value of the high-speed counter is 
changed with the following methods.
 • When the current value of a high-speed counter was rewritten with the HCMOV instruction.
 • When the current value of the high-speed counter is reset with the RST instruction or the ZRST instruction (when the FX3 

compatible high-speed counter function is valid)

 • When the current value of the high-speed counter was changed by a self-reset. (When the preset input comparison function 

is disabled)

 • When high-speed counter current value is the ON or OFF output result of the comparison of the DHSCS, DHSCR, DHSZ 

instructions.

 • When high-speed counter current value is the ON or OFF output result of the comparison of a high-speed comparison 

table.

■Preset input comparison operation

When the preset input comparison is enabled and preset control switching is set to constant when ON, the preset input 
comparison does not operate.

■Timing at which the instruction is enabled

The DHSCS, DHSCR, DHSZ instructions are enabled at the END instruction for the scan in which the instructions are driven. 
Even when the comparison value is changed, it is updated at the END instruction for the scan in which it was changed .

■Configuring high-speed comparison tables with parameters

Operations of DHSCS, DHSCR, DHSZ instructions of the same comparison value are executed after high-speed comparison 
tables set with parameters. The high-speed comparison table is processed sequentially from the top of the table.

Counting

• HIOEN instruction
• SPD instruction

• HIOEN instruction
• SPD instruction

Comparison processing

• HIOEN instruction
• DHSCS, DHSCR, DHSZ instructions

• HIOEN instruction
• DHSCS, DHSCR, DHSZ instructions