Mitsubishi ALT command

Mad_Poet · May 29, 2018

Dear sirs,
I am trying to use one button - first push a relay needs to latch on, and second push the relay needs to latch off.

I am using a Mistubishi FXon - 40MR-ES PLC and the 'ALT' command, according to the documentation, should be exactly what I need.

Except it doesn't. It looks like the ALT function simply keeps toggling the
relay on and off and on and off . . . while the button is pushed meaning
it is multiple guess as to whether or not my 'output' is properly latched on or off.

Ronnie Sullivan · May 29, 2018

Use ALTP
The p means 'one shot.... Or Pulse if you like.
It will then not go true until next time it is executed.

lfe · May 29, 2018

Use ALTP instead ALT and the output relay will toggle only one time at the rising edge of the input command.

Mad_Poet · May 29, 2018

Oddly enough, ALTP refuses to work for me.

I finally figured out that I can use the input to latch a relay on, which starts
a one second timer. When the timer ends it unlatches the relay and triggers
the ALT function which then toggles my output.

I'm hoping I've attached a file with my ladder logic.

Seems to work OK.
Poet.

Ronnie Sullivan · May 29, 2018

I did actually wonder if the p instruction worked with that model of plc....It's very old.
But the PLS instructions does.
So it would be
LD X5 OUT PLS M4
LD M4 OUT ALT Y6

Mad_Poet · May 30, 2018

Dear Ronnie,
The PLS instruction does not seem to work either. When I try to use the ALTP or the PLS
it comes up with this 'Instruction Help' box with no help.

I thought maybe I was using a very old version of GX Developer - Version 8.25B.

Then I tried a newer PLC. A Mitsubishi FX1n-14MT-ESS/UL.
Both the ALTP and the PLS instructions work in it.

Note the up going arrow in line 6, and the ALTP in line 11. Both work as advertised (in the FX1n). Neither will work in that FX0n.

But, that ladder I posted earlier works quite well so the project moves forward.
Poet.

Ronnie Sullivan · May 30, 2018

I assure you the PLS instruction works on an FXoN.

SagittarianPLC · Jun 2, 2018

PLS is a quite basic instruction, Should really work with any basic model.

Mad_Poet · Jun 4, 2018

Dear Sirs,
All I can tell you, is that when I tried both the ALTP and the PLS
on that FX0n, they did not work.

When I tried them on the FX1n, they both worked as advertised.
In post six, I put the ladder logic from the FX1n. I could not get
the ladder to go in on the FX0n - it comes up with 'instruction help' -
Which was no help.

But that's OK. The ladder I posted before that, with the one second timer,
works quite well so I'm happy now.
Thanks,
Poet.

JRoss · Jun 4, 2018

Time to upgrade...

goghie · Jun 15, 2018

Is it original FX0N-40-MR/ES or China copy?

Mad_Poet · Jun 19, 2018

Dear Goghie,
My FX0n has 'Made in Japan' printed on it.
I think it came out of a machine that would have been built before 2004 . . .
Poet.

Mad_Poet · Jun 20, 2018

Hmmm.
Looks like that FX0n could have been manufactured as early as 1993.

Been a long time . . . I know my FX0n PLC came out of a machine we removed
and replaced with a newer better type machine to do the same thing. I Just
don't remember when.
(And the beast still works.)
Poet.

Mitsubishi ALT command

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