Mitsubishi Electric MELSEC-Q Series - Devices and Instruction Symbols in Programming

14
6 Programming
Create a program (sequence program) for sequence control.
 "Devices" and "instruction symbols" in programming
Combine "devices" and "instruction symbols" to create a sequence program.
1. Devices
Devices include bit devices and word devices.
1 Bit device: handles one-bit information such as ON/OFF of a switch or a lamp.
Examples of bit device
2 Word device: handles 16-bit information such as numeric values and character strings.
Examples of word device
Device name
Device
symbol
Description
Input X Receives a signal from an external device such as a switch.
Output Y Outputs a signal to an external device such as a lamp
Internal relay M Temporarily saves data status in programs.
Timer (contact) T
Used to measure time (when the set time comes, the contact is set to
ON).
Counter (contact) C
Used to count the number of times the input condition turns from OFF
to ON (when the counter reaches the set number, the contact is set to
ON).
Device name
Device
symbol
Description
Data register D Registers numeric values and character strings.
Timer (current value) T Used to measure time (stores the current value of measuring time).
Counter (current value) C
Used to count the number of times the input condition turns from OFF
to ON (stores the current value of the counter).
ON/OFF of a switch
ON/OFF of a lamp
Numeric value Character string