output problem

In a ladder_diagram can we use an output(coil)in more than 1 rung???????????????
If no,Then Why????

What particular PLC are you using?

OG

OMRON cpm2A-40CDR

MR!!!!!!!!!
Where have u gone????????

In some PLC it is allowed to use Output coil twice but it create double coil syndrome problem. Refer this Post for detail http://www.plctalk.net/qanda/showthread.php?p=26293#post26293

You can use the same output number in several rungs with this PLC. However, it is not good practice. The last incidence of the output in the program will overwrite all other incidences.
It is not good practice!!

Generally its a case of "The last one wins" as the state of the output in the image table table at the end of the scan is then transferred to the output card.
If you go to youtube and search for Ron Beufort, his training videos explain this well.
Alternatively you can use a Set / Reset coil or Latch / Unlatch, this is also explained in the videos.

Hope this helps

LH

BobB said:

You can use the same output number in several rungs with this PLC. However, it is not good practice. The last incidence of the output in the program will overwrite all other incidences.
It is not good practice!!

Click to expand...

Don't know if there are jump instructions in this PLC, but multiple use of the same coil is quite often used in sequencing programs with no ill effect and no 'bad practice' syndrome.

Also as above using latch and unlatch.

Hi
I agree with the jump instructions comment but in this case i would say good practice would be to use diffent internal marker coils, and then parallel these to the real output.
I have worked on a program using jumps for sequencing and would not recommend the method where the same coils are used over and over.........clever technique but a pita to faultfind

TriStation 1131 Developer's Guide, v4.6

While reading through this guide I came across this
"Enable Multiple Writes
The Enable Multiple Writes property specifies whether a tagname can be written to multiple
times from programs in the application. If this property is not selected and the tagname is
written to more than once, an error is displayed when the program is compiled.
The default is cleared, which means the tagname can only be written to once in an application."

During programming the Triconix PLC I noticed that If the Enable Multiple writes option was not selected the program gives an error if an output is written more then once. And if enabled I think double coil syndrome happens.