charger66

Output not on

11 posts in this topic

New to Omron, old to programming.

Having an issue with an output. And, it is only used once in the program. it is not a set output.

The line of code is branched into a manual string and then an automatic string.

The manual branch works the output goes green in the ladder, looking at the i/o map it goes true and the cylinder move as it should.

The branch under the manual conditions are for auto mode, when in auto and the conditions are true, the rung turns green showing the output as "On" but in the I/O map the bit is still false....and the cylinder does not move......WTF??

anyone have any suggestions?

 

Thanks

jeff

 

Edited by charger66

Share this post


Link to post
Share on other sites

Is the inside of the coil colored in, or is it blank, like this:

5ac68434d06a5_Coilnoton.jpg.d30baf3ca5a4

 

If the inside of the coil is not on, then the condition that turns it on is FALSE when the rung in question exectues (rung 1 in this example) and then is true after the rung in question.  Since Sysmac Studio cannot show the value as each rung executes and only shows the value of all bits/words at the end of the scan, it looks like the coil should be on.

There are a few other possibilities, but start here.

Share this post


Link to post
Share on other sites

Hi Michael,

I will look at that this morning. I can't remember if looked like that. I will take a photo and upload.  Thinking about this last night, I modified the program and added a few sections in program0, the program is setup in the tasks area, but i don't see all the sections. Is that normal?

Thanks

 

Jeff

Share this post


Link to post
Share on other sites

You are correct sir... the inside is not green.

I have read and re-read you first post. I don't understand, if the logic is true, the output should be on regardless of scan time.. And why will it not become true on the next scan?

IMG_2466.JPG

Edited by charger66
additional thoughts

Share this post


Link to post
Share on other sites
2 hours ago, charger66 said:

I have read and re-read you first post. I don't understand, if the logic is true, the output should be on regardless of scan time.. And why will it not become true on the next scan?

It is difficult for me to see what the contacts are in your rung, but one (at least) of the three contacts in the lower branch of the rung does this (lets just call it BitA):

 

BitA is turned OFF by the ladder code somewhere before this rung 

When this rung is scanned, BitA is OFF, therefore the coil does not turn on.

BitA is turned ON by ladder somewhere after this rung.  

 

Sysmac Studio can only show the status of the bits at the end of the scan as bits can change too fast during the scan to display this, so it looks like the coil should be on.  However, when the rung was scanned, the logic was NOT true and the bit is NOT on.  

The output bit is not turned on for the next scan because when the ladder scans from the beginning, BitA is turned off by the ladder again and is still off when the rung in question is scanned.  My picture above shows this.  The first rung Resets the OnCondition bit.  When the second rung is scanned, OnCondition is FALSE, so Outbit is NOT turned on.  The third rung Sets OnCondition to True.  Sysmac Studio displays the status of the bits at the end of the scan and therefore it looks like Outbit should be on.  When the ladder scans again, OnCondition is Reset to FALSE again and Outbit NEVER turns on.

Share this post


Link to post
Share on other sites

Ok, I sort of understand what you are saying, but in my case the logic controlling the should not be true then false between scans. Are you saying that a rung is only true while being scanned?

The two bits in my photo, after the auto mode bit, the first (A) would turn it output on, and the second(B) would turn it off later. (A) an internal contact off a SET output function. DOes the whole line of code have to remain true in that line for the set bit output to be true? if that is the case what is the purpose of a set bit? and why would you need a reset bit?

Confused in Canada...lol

Share this post


Link to post
Share on other sites

Can you post your code for us to look at it?

If you don't want to post it, you could message it to me and I will look.

 

Share this post


Link to post
Share on other sites

I think just found my problem.... Needed to look at it differently, with my butt on my couch, not in front of the machine. I will report back on Monday.

Share this post


Link to post
Share on other sites

Hey Michael,

I know this is an old post, but I just want to make sure I'm understanding this correctly. I'm typically all AB, so I'm on the Sysmac learning curve.

In your example the OnCondition output is set as a Reset Instruction (Similar to a OTU in Studio 5000) so it is turning the output to 0, so when it scans rung 2 the input is off. However in Rung 3 the OnCondition output is set as a Set Instruction (Similar to a OTL in Studio 5000) and turns the output to 1.

 

Thank you,

-Andrew

Studio Latch and Unlatch broken logic.PNG

Share this post


Link to post
Share on other sites

What you described is correct.

The rungs you show are identical to Michael's example.

Logix and Sysmac PLC scans are the same. They scan from left to right and top to bottom.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now