Mitsubishi Digital Electronics FX Manual

A SERVICE OF

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FX Series Programmable Controllers Devices in Detail 4

4-8

4.4.3 STL Step Relays

States (S) are ver

y

important devices when

pro

g

rammin

g

step b

y

step process control. The

y

are

used in combination with the basic instruction STL.

When all STL st

y

le pro

g

rammin

g

is used certain states

have a pre-defined operation. The step identified as

in the fi

g

ure 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

thou

g

h remainin

g

state steps are used in an STL

format, the

y

still retain their

g

eneral or latched

operation status. The ran

g

e of available devices is as

specified in the information point of the previous

section.

Assigned states:

• When the applied instruction IST (Initial STate function 60) is used, the followin

g

state

devices are automaticall

y

assi

g

ned operations which cannot be chan

g

ed directl

y

b

y

a

users pro

g

ram:

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 pro

g

ram sequence

Monitoring STL programs:

• To monitor the d

y

namic-active states within an STL pro

g

ram, special auxiliar

y

rela

y

M8047 must be driven ON.

STL/SFC programming:

• For more information on STL/SFC st

y

le pro

g

rammin

g

, please see chapter 3.

IST instruction:

• For more information on the IST instruction please see pa

g

e 5-67.

S2

X0

X1

X2

X3

1

S20

S21

S22

Y0

Y1

Y2