SQL instruction in PLC is

Sequencer instructions are used to control automatic assembly machines that have a consistent and repeatable operation using 16-bit data.

Sequencer SQL (Sequencer Load):

• SQL is an output instruction used to capture reference conditions by manually stepping the machine through its operating sequences and loading I/O or storage data into destination files.
• It transfers data from the input source module to the sequencer file.
• The instruction functions much like a file-to-word transfer instruction.

Sequencer Output (SQO): It is an output instruction that steps through a sequencer file of 16-bit output words whose bits have been set to control various output devices.

Sequencer Input (SQI): It is an input instruction used to monitor machine operating conditions for diagnostic purposes by comparing 16-bit image data through a mask, with data in a reference file.