Mitsubishi Electric MELSEC iQ-R Series Reference Manual page 22

High-speed counter module
The value is latched in synchronization with the falling edge of the inter-module synchronization control signal. The latched
value is stored in the buffer memory. The normal count operation is executed even when using the inter-module
synchronization signal. The latch target and storage destination buffer memory differ according to the operation mode.
Operation mode
Pulse count mode
Pulse measurement mode
*1 The value is updated only at the falling edge of the inter-module synchronization control signal regardless of the ON/OFF state of the
count enable instruction pulse measurement instruction.
■Pulse count mode (Synchronization latch counter function)
The latest current counter value is retrieved at the inter-module synchronization cycle start timing, and is held during the inter-
module synchronization cycle. By reading the synchronization latch counter value from the inter-module synchronous
interrupt program, multiple modules can read the retrieved current count value at the same timing.
High-speed counter module No.1 CH1
Present value
Synchronization latch count value
High-speed counter module No.2 CH1
Present value
Synchronization latch count value
5 FUNCTION
20
5.1 Fixed Cycle Synchronization Function
Latch timing
Falling edge of inter-module
synchronization control signal
Falling edge of inter-module
synchronization control signal
Inter-module
synchronization cycle
Inter-module synchronous
interrupt program
CPU module Input Operation
refresh processing
Read a synchronization latch count value.
Count value 1
Count value 1
Count value 1
Latch target
Current counter value
Measured pulse value
Inter-module synchronous
interrupt program
Normal program
Output Input
refresh refresh
Read a synchronization latch count value.
Count value 2
Storage destination buffer memory name
Synchronization latch count value
Synchronization measured pulse value
Inter-module
synchronization cycle
Normal program
Operation Output
processing refresh
Count value 2
Count value 2
*1