Studio5000 I/O Buffer

[GaryS]

On a Logix processor buffering the I/O is not necessary
the I/O has its own processor to read and write to the I/O tree
there is nothing to be gained by buffering

 

[rdrast]

On a Logix processor buffering the I/O is not necessary
the I/O has its own processor to read and write to the I/O tree
there is nothing to be gained by buffering

I disagree.


Need to reassign an IO point? Bufferred: Change it in one and only one place. Unbufferred: Search and make multiple replacements. Ditto if you need to change input types, voltage, current, TC, RTD, AC/DC, etc.


Also, as I said above, it makes it extremely easy to see exactly what is used, on every rack/IO module, since I still assign all unused points to dummy registers in the buffer routines.


When memory and scan times were an issue, we used IO directly just to save precious bits, and reduce scan times. With modern processors, there is no reason for such minuscule optimizations.

 

[Ken Moore]

I always buffered in a stand alone routine. Then you can not scan the routine and easily manipulate the I/O for testing.

 

[mylespetro]

I always buffered in a stand alone routine. Then you can not scan the routine and easily manipulate the I/O for testing.

I don't think I've ever considered that, that's a great tool to have for bench testing and troubleshooting.

 

[plvlce]

I always buffered in a stand alone routine.

This is what I do. Well, I actually use a stand-alone program with multiple routines -- one for local I/O and a separate one for each set of networked devices.

 

[IndianaCoder]

2 points.
1) I believe 5000 updates IO with Priority 6 or 7, so if you don't use a continuous task you can set your priority of the program to allow I/O to interrupt the scan and update or force to wait. Now I am not sure how the newer processors do that because I believe the latest series has a different processor that just scans I/O.

2) For Buffering, does anyone else find it annoying that you can't just force the input or output on anymore?
It is a small thing but I find it tedious to cross reference the mapped tag to find the real tag then force that on, this is typically only an issue during debug, but debug is also a huge chunk of my job working for SI.

 

[GaryS]

Need to reassign an IO point? Bufferred: Change it in one and only one place

Thats what Alias is for use the Alias your program and reassign the to true I/O as needed

 

[rupej]

Need to reassign an IO point? Bufferred: Change it in one and only one place

Thats what Alias is for use the Alias your program and reassign the to true I/O as needed

But aliases confuse people and can't be changed online, right? Also, no easy way to unlink from the true I/O for testing or simulation.

 

[nyanpasu]

What I do is feed the card/module I/O tags into different AOIs at the controller scope that are named after the print tags into a IO buffering task, organized by type of module (local, remote, drives, valve banks, etc) and then instance (communication module, singular drive, etc). These handle on/off delays, device interlocks, manual modes, forces, simulation, scaling/signal conditioning if necessary, etc, and of course also buffer the I/O.

Then I alias the AOI to a program tag with a descriptive name (ie. TankOutletPump in program Tank100). I link the alias tags to the HMI and not the base buffering AOI, so I don't have to hunt around the program to remember which valve number is where and does what.

This way, you have descriptive names for the aliased tags and can also cross-reference with the electrical prints if necessary using the base tag. I can also use an Excel macro to generate the first layer and when reusing programs I just have to reassign the aliased tags to new I/O.

Also, if an I/O point does fail, you can just change the I/O tag inside the AOI. No download is necessary in the immediate. You can even rename the AOI tag online and the alias address on the alias tag follows, so no download may be necessary ever, but I'd have to check if you can still do that when an HMI is actively RWing into the alias tag.

It's a bit heavyset but works for me.

 

[caro_0126d]

Please help with decimals

Guys I need this ,..... I have a analog input and adter scaling the number is for example 4.5726366387213
i need let the number only as 4.57
how i do that ?
Please

 

[Steve Bailey]

caro_0126d, you posted the same question in an old thread. Now you've posted in an unrelated thread. You were given good advice in the other thread. That was to start a new thread by going back to the main forum page:

http://www.plctalk.net/qanda/forumdisplay.php?f=2

and clicking the button labeled "Start a new thread".

One other piece of advice: Specify the equipment you're working with. Are you trying to limit the number of decimal places displayed on an HMI screen? On most brands that's pretty simple to do, but the details of how to do it vary from one brand to another.