Mitsubishi Digital Electronics FX0S Manual

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FX Series Programmable Controllers Points Of Technique 10

10-2

10.3 Using The Forced RUN/STOP Flags

10.3.1 A RUN/STOP push button configuration

The FX pro

g

rammable controller has a sin

g

le RUN terminal. When power is applied to this

terminal the PLC chan

g

es into a RUN state, i.e. the pro

g

ram contained is executed.

Consequentl

y

when there is no power 'on' the RUN terminal the PLC is in a STOP state.

This feature can be utilized to provide the FX PLC with an external RUN/STOP - push button

control. The followin

g

PLC wirin

g

and pro

g

ram addition are required.

Explanation:

Pressin

g

the RUN push button sets the PLC into the RUN state. This means M8000 is ON.

Followin

g

the pro

g

ram, M8000 activates both M8035 and M8036. These two special auxiliar

y

devices set the PLC in to forced RUN mode. Releasin

g

the RUN push button would normall

y

return the PLC to the STOP state, but because the two auxiliar

y

coils, M8035 and 36 are ON,

the PLC remains in RUN. To stop the, PLC pressin

g

the STOP push button drives an input ON

and consequentl

y

M8037 turns ON. This then automaticall

y

forces OFF both M8035 and 36

and resets itself. Hence, the PLC is in its STOP status and awaits the c

y

cle to be

g

in a

g

ain.

Input priority:

• The STOP input is onl

y

processed after the pro

g

rams END statement has been reached -

this is because the ph

y

sical input used, i.e. an X device is normall

y

updated and processed

at that time. Therefor, the RUN input is

g

iven priorit

y

when both RUN and STOP inputs are

g

iven simultaneousl

y

.

•To

g

ive priorit

y

to the STOP input and provide a 'safer' s

y

stem, some form of mechanical/

circuitr

y

interlock should be constructed between both RUN and STOP inputs. A ver

y

simple example is shown in the wirin

g

dia

g

ram above.

• For push-button control to operate correctl

y

, the user must set the RUN/STOP switch on

FX

2C

and FX

2N(C)

units to the STOP position.

•FX

2N(C)

units do not have a RUN terminal. One of the inputs X0 to X17 (X0 to X7 for FX

2N

-

16M) on the MPU should be confi

g

ured as a RUN terminal in the parameter settin

g

s.

M8000

M8035

X1

M8036

M8037

24V S/S0V RUN X0 X1

RUN

STOP

FX base unit configured as source

input (example only)

Forced STOP

command

Forced RUN

command

Forced RUN mode