Convenient Functions For Output Processing; Functions For Supporting Sequence Control - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
5. Three types of "interrupt" functions for receiving short-period pulses and priority
processing
1) Input interrupt
Signals from specific input relays are monitored. At the rising edge or falling edge of the monitored input,
a specified interrupt routine is executed with highest priority.
2) Timer interrupt
Specified interrupt routines are executed with highest priority at every specified time.
3) Counter interrupt
Depending on the present value of a high speed counter, a specified interrupt routine is executed with
highest priority.
*1. This function is supported only in FX
6. Pulse width/Pulse period measurement function
The pulse width or pulse period of pulses input from input terminals (X000, X001, X003 and X004) of the main
unit can be measured in units of 10µs.
The pulse width/pulse period measurement function is available in a wide range of applications because the
pulse width or pulse period can be easily taken in accordance with the setting of special auxiliary relays.
The input signal delay time can be measured using two or more input terminals.
*1. This function is supported only in FX
2.1.2

Convenient functions for output processing

1. "I/O refresh" function for outputting the latest input information
The input terminal information of the PLC in the batch refresh method is input at one time by the input image
memory before operation in the step 0. The output information is output at one time when END instruction is
executed.
I/O refresh instruction can get the latest input information and immediately output the operation result during
sequence operation.
2. "Pulse output" function for pulse train output control
3. "Positioning" function for positioning control
2.1.3

Functions for supporting sequence control

1. "Constant scan" mode for making the operation cycle of the PLC constant
The operation cycle in the PLC adopting the cyclic operation method varies depending on the contents of the
program execution.
In the constant scan mode (M8039 and D8039), the operation cycle can be made constant. As a result,
instructions executed in synchronization with the operation can be processed in a constant cycle.
2. "All outputs disable" mode for turning OFF all output signals
When the special auxiliary relay M8034 is driven, the output latch memory is cleared. Accordingly, all output
relays (Y) turn OFF while the PLC is continuing its operation.
However, the status of output relays (Y) in each device image memory is not cleared. As a result, when
devices are monitored using a programming tool, they may be regarded as the ON status.
26
*1
/FX
3U
PLCs.
3G
→ Related instructions: Pulse Y Output PLSY (FNC 57) and
→ Related instructions: DOG Search Zero Return DSZR (FNC150),
Interrupt Positioning DVIT (FNC151), Zero Return (FNC156),
2.1 Introduction of Convenient Functions
PLCs.
3UC
*1
→ Related instruction: Refresh REF (FNC 50)
Acceleration/Deceleration Setup PLSR (FNC 59)
Variable Speed Pulse Output PLSV (FNC157),
Drive to Increment DRVI (FNC158) and
Drive to Absolute DRVA (FNC159)
2 Overview (Sequence Program)
→ Refer to Chapter 36.
→ Refer to Section 36.8.