how to find forces in rslogic 5000

hi guys
i have a force light on our compactlogix, i have looked in the plc ladder program and can not see any forces, i have looked at the control tags list and there is nothing in the force mask (i think is meant to say forced in the force mask)i have done the same in program tags,but i am at apoint where i am not to sure what to look for. does anyone have any ideas that could help
thanks stu

if the LED is on "SOLID GOLD" then "forces are enabled" ...

BUT ...

with ControlLogix and CompactLogix you MIGHT NOT actually have any forces installed ... specifically, the LED can be ON even if there are NO forces actually present/installed ...

tip: make SURE that the "SHOW" legend at the top of the tag listing says "Can Be Forced" before you check the "Force Mask" column ... it's OK if it says "Show All" too - but be sure that you're not looking at just part of the list ...

tip: if it's SAFE to do so, try disabling the forces ... if the LED goes completely OFF, then there are no forces present ... but ... if the LED starts to flash gold ON and OFF, then there are forces somewhere - keep looking ...

Do you have the "Force Mask" column under controller tags? If not right click one of your column headings and select "Toggle Column" then put a check by "Force Mask".

Also you will only have data by physical I/O that can be forced.

yes the light is solid gold?, thanks, what do you mean (with ControlLogix and CompactLogix you MIGHT NOT have any forces installed ?) thanks stu

yes i have the "Force Mask" column under controller tags thanks stu

ControlLogix and CompactLogix will allow you to ENABLE forces - even though there are NO forces installed ...

this is similar to most of the MicroLogix processors ... there the forces are ALWAYS "enabled" - whether any forces have been installed or not ...

note that with the PLC-5 or SLC-500 platforms, when there are NO forces installed, then forces can NOT be "enabled" ...

Hi ron
What do you mean my forces installed??
Do you mean enabled forces or is it an extra install from the disk

Thank you for your time
Stu

What Ron means is that you can have forces in the force mask area of the controller, and NOT have them enabled.

Getting forces to work is a 2-stage process.....

1. You "install" the forces into the force mask area....

2. You then "enable" i/o forces....

This allows you to set up multiple forces if need be, and then turn them all on at once - it may not be appropriate to put forces on one-by-one.

In my opinion, you should never do either of the following on a long-term basis...

1. Have forces "installed" and not "enabled"

If there are disabled forces already in the controller, and you want to force something else, you have to remember to remove the already-installed forces before you install and enable your new force - otherwise you will enable the old force, which may not be a good thing to do.

2. Have forces "enabled" with none "installed"

If you forget to check that forces are enabled, and you install a force, it takes effect immediately. This can be inapproriate if you want to do multiple forces.


Safest is to remove all forces, AND disable forcing.

What do you mean my forces installed??
Do you mean enabled forces or is it an extra install from the disk

Click to expand...

in regards to "forces" - RSLogix5000 uses the word "Installed" to mean "Present" or "Existing" ...

maybe this will help ... reference the figure below ...

(1) this legend is also a BUTTON that you can press to change the menu being displayed ...

depending on your system's conditions, this legend will say either "Forces" or "No Forces" ...

(2) this little triangle is the "Force Icon" ...

clicking this icon will pop up a menu and let you control the I/O Forces ... note that you could also control SFC (Sequential Function Chart) forces if you were working with that type of programming ...

(3) in the example shown, this legend is telling us that we currently have at least one I/O Force "Installed" - or in other words, "present" - or in other words, "existing" ...

the little square icon is supposed to mirror whatever the "Force" LED on the front of the processor is doing ... either "Off" – or on "Solid Gold" – or "Flashing On and Off" ...

(4) NEVER (I repeat, NEVER) trust this piece of junk ...

this icon offers to "Find All Forces" – but it ONLY looks through your routines – NOT through the tag listing ... that means that someone might have left a force in the tag listings for an input or output which might not actually be used in your programming code ... this "Find All Forces" piece of junk would MISS FINDING THAT FORCE – and leave you holding a smoking gun when you proceed without knowing about said force ... there is no way for that scenario to end well ...

and in some versions of RSLogix5000, this "Find All Forces" piece of junk also has a nasty habit of hanging up your "Search" feature ...

suggested reading:

http://www.plctalk.net/qanda/showthread.php?p=441852&postcount=11

(5) you can push this button and set it to show "Can Be Forced" ... this would be very helpful if you had a large system with 30 or 40 thousand tags to look through ... if you choose to not set it to "Can Be Forced" – make sure that it says "Show All" instead ... anything else could leave some of your forces off the list ... (that would be "bad") ...

important: if you change the setting of this button, be sure to set it back to "Show All" when you're finished ... it's quite easy to miss the fact that your tag list might not include ALL of your tags ...

(6) make sure that the "Scope" is set for the "Controller" level ...

note that anything that can be forced must be scoped at the "Controller" level ... yes, there might also be aliases scoped at the "Program" level which could be forced – but in that case the "base tag" will still be scoped back at the "Controller" level ... secret handshake: you don't have to search through all of the "Program" tags when looking for forces ...

(7) this is the "Force Mask" where the forces will actually appear ...

make sure that this column is set wide enough to adequately display the information ... it's easy to get confused because RSLogix5000 uses a PERIOD to mean "not forced" – but they also use THREE PERIODS (an ellipsis) to mean "my column is not set wide enough" ...

(8) here the word "Forced" is telling us that something in tag "Local:1:I" is being forced either ON or OFF ...

(9) by "drilling down" we can see a "1" that means that a particular input signal in tag "Local:1:I.Data" is being "Forced ON" ...

a "0" in this legend would mean "Forced OFF" ... a "." here means "Not Forced" ... (again, assuming that the column is set wide enough) ...

(10) by "drilling down" another step we can see the same "1" in another format – which is a representation that the specific input signal from "Local:1:I.Data.2" is being "Forced ON" ...

now we would need to go down through the rest of the "Force Mask" column and make sure that there are no OTHER forces lurking in the underbrush ...

caution: I never let my students use the scroll bars or mouse wheel for moving down through the column ... depending on how you're communicating with the processor, it's possible to scroll down too fast for the screen to update ... you could conceivably miss some forces that way ... I recommend that you use the "Page Up" and "Page Down" keys on your keyboard – and give the screen plenty of time to update between key presses ... we're looking for loaded hand grenades here ... let's take our time and be certain that we're not missing anything ...

I hope this helps ...

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Correct me if am wrong so

Forces installed = Forces are there in the processors but they are activated.

Forces enable = they are active and are forced.

So the question is when does the led on the processor lights up. When forces installed or enabled?

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the gold/amber "Force" LED will flash ON and OFF when forces are installed/present - BUT those forces are not enabled ...

in this condition there ARE forces present – but they are NOT affecting the operation of the system ...

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the gold/amber "Force" LED will be solid ON if forces are enabled ...

the tricky part is that in this condition:

(1) there MAY be forces present - or
(2) there may NOT be any forces present ...

IF (big IF) there are any forces installed/present and the gold/amber "Force" LED is STEADY ON, then the forces ARE affecting the operation of the system ...

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look at it like hand grenades ... forces are so dangerous that they have a "safety pin" that needs to be pulled in order for the force to take effect ... we "pull the pin" by "enabling" the forces ...

the scariest part is that when you pull ONE safety pin, then ALL of the pins are pulled ... specifically, you can NOT selectively "enable" your force for the alarm lamp – while leaving Bubba's force for the hydraulic ram "disabled" ...

Ron, re post #9: Another Tour de Force! Thank you for taking the time to put this up. It's already printed for bed time reading. All the best, Steve.

For anyone following this post, please read and understand !!

FORCING IS FORCING

You are asking the program, the system, the application, the machine, the process, etc., to absolutely IGNORE something it was designed to monitor or control.

Forcing differs between manufacturers. I can only speak with confidence of Allen-Bradley hardware, and there are some subtle differences between their platforms.

Golden rules if you want/need to use forcing...

1. Learn the system you are using, ensure you understand it.
2. Use forces only when absolutely necessary.
3. Explore the use of other techniques, perhaps an online edit...
4. Inform others (that's everybody) if you need to leave a force in place.

Just remember that the system/machine/process probably went through many man-hours of testing/simulation before acceptance on site - one force and it could have been all in vain !

I speak from experience - forcing is the most dangerous thing you can do on a running system, yet it is a function that can be done by anyone who has access to the controller.

careful is - as careful does ...

well, while we're on the subject of being careful (and always an excellent subject to be sure) here is one example of how easy it is to get a FORCE – even when you didn't plan to use one ...

this one comes up in just about every class (and usually more than once) ... the student is always puzzled as to where the "mystery" force came from – because usually he fails to notice how the columns have been shifted while working in the tag listing ... this "extra" force just sort of lurks in the underbrush – waiting patiently for the next "enable forces" operation to come along ...

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and one more ...

and this next example is one of my personal favorites ... try it yourself sometime when you've got a SAFE situation to play around with ... too much of this stuff and I have to sleep with the lights on at night ...

notice that just holding the mouse ONE PIXEL too high when you Right-Click on an address can select an "innocent bystander" address on the NEXT RUNG ABOVE ... now suppose that you fail to notice the shift in focus - and just go merrily on your way by selecting a "FORCE" operation from the popup menu ...

there are two basic types of students who make this particular mistake ...

(1) young-uns who tend to shoot from the hip - and just click-click-click away like RSLogix is some type of video game ... "game over?" ... no problem, dude – just start another one ...

and then ...

(2) old guys who don't have their eyeglasses up to snuff ... to them the mouse looks like a little white fuzzy blob moving around on the screen – and they fail to see the little pointy end that is supposed to "stick" the target ... you can watch these folks just perch the mouse right on top of their targets – instead of actually "pointing" the way the mouse is intended to be used ...

party on ...

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