Creation Of Step Ladder Program (Sfc Program → Stl Program) - Mitsubishi Electric FX3G SERIES Programming Manual

Programmable controllers

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Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

Creation of step ladder program (SFC program → STL program)

The figure on the left shows one state relay extracted as an example from an SFC program.

Each state relay has three functions, driving a load, specifying a transfer destination and specifying a transfer

The step ladder shown on the right expresses this SFC program as a relay sequence.

In this program, a load is driven, and then the ON status is transferred.

In a state relay without any load, the drive processing is not required.

For the program creation procedure, refer to the description on SFC programs.

SET and RST instructions for a state relay are two-step instructions.

• When every state relay used in an SFC program is defined, programming is complete.

• Program a step ladder program starting from the initial state relay in the order of state relay ON status transfer.

Make sure to put the RET instruction at the end of a step ladder program.

Program with jump/repeated flows

1. Program for the transfer source

Use OUT instruction in the jump/repeated part.

→ For the program creation procedure, refer to Subsection 35.1.3.

→ For the handling and role of initial state relays, refer to Subsection 35.1.4.

→ For latched (battery backed) type state relays, refer to Subsection 35.1.5.

The above program can be expressed in the list format

(list program) shown on the left.

The segment from the STL instruction to the RET

instruction is handled as a step ladder program.

Jump/repeated part

35 SFC Program and Step Ladder

→ For RET instruction, refer to Subsection 35.1.6.

Use OUT instruction in the jump/

repeated part.

35.2 Step Ladder

Fx3u series Fx3uc series