FX Series Programmable Controllers

Devices in Detail 4

4.4.3STL Step Relays

State s (S ) a re v ery im p orta nt de vic es w he n programming step by step process control. They are used in combination with the basic instruction STL.

When all STL style programming is used certain states have a pre-defined operation. The step identified as in the figure opposite is called an ‘initial state’. All other state steps are then used to build up the full STL function plan. It should be remembered that even though remaining state steps are used in an STL format, they still retain their general or latched operation status. The range of available devices is as specified in the information point of the previous section.

1

S2

X0

S20

X1

S21

X2

S22

X3

Y0

Y1

Y2

Assigned states:

• When the applied instruction IST (Initial STate function 60) is used, the following state devices are automatically assigned operations which cannot be changed directly by a users program:

S0

: Manual operation initial state

S1

: Zero return initial state

S2

: Automatic operation initial state

S10 to S19 : Allocated for the creation of the zero return program sequence

Monitoring STL programs:

• To monitor the dynamic-active states within an STL program, special auxiliary relay M8047 must be driven ON.

STL/SFC programming:

• For more information on STL/SFC style programming, please see chapter 3.

IST instruction:

• For more information on the IST instruction please see page 5-67.

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Mitsubishi Electronics FX1S manual Assigned states, Monitoring STL programs, STL/SFC programming, IST instruction