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

Flag that detects counter value overflow of high-speed counter.

■Corresponding devices

The device numbers corresponding to each channel are as follows.

■Operation Description

The content of the operation when ON and when OFF is as follows.

 • Does not operate when ring length setting is enabled.
 • These devices also operate when the FX3 compatible high-speed counter function is valid.

■Update timing

The timing of device update is as follows.

Flag that detects counter value underflow of high-speed counter.

■Corresponding devices

The device numbers corresponding to each channel are as follows.

■Operation Description

The content of the operation when ON and when OFF is as follows.

 • Does not operate when ring length setting is enabled.
 • These devices also operate when the FX3 compatible high-speed counter function is valid.

■Update timing

The timing of device update is as follows.

SM4532

SM4533

SM4534

SM4535

SM4536

SM4537

SM4538

SM4539

Overflow occurs
(Current value counted = +1 past maximum positive value)

Overflow does not occur

• Overflow occurs (This is updated with the END processing. When the FX3 

compatible high-speed counter function is valid, the updating is made also 
when instruction UDCNTF instruction is executed ON.)

• When OFF by the user
• Power ON, reset
• STOP/PAUSE

RUN

• SM50 turned ON

SM4548

SM4549

SM4550

SM4551

SM4552

SM4553

SM4554

SM4555

Underflow occurs
(Current value counted = -1 past maximum negative value)

Underflow does not occur

• Underflow occurs (This is updated with the END processing. When the FX3 

compatible high-speed counter function is valid, the updating is made also 
when UDCNTF instruction is executed ON.)

• When OFF by the user
• Power ON, reset
• STOP/PAUSE

RUN

• SM50 turned ON