PLC-2 project given a go. OH NO!

[Skiroy]

The old ZCL (Zone Control Last State) instruction is a "freeze" relay. You use it in pairs, similar to the MCR. From the rung below the first ZCL to the next ZCL (the ZCL "zone"), when the ZCL goes false or is de-energized by the trigger input(s), all outputs between the ZCL instructions are left in their last state (not changed from either on or off) even though their rung inputs may change while the ZCL trigger is on.

To simulate it in a SLC 500 program, one way is to set up a subroutine that includes all the rungs in the ZCL zone. Then use the old ZCL trigger input(s) to call the new subroutine. If the subroutine is not called, any outputs inside the subroutine are left in the last state before the subroutine call.

The first example is probably really the beginning of a new MCR group after a ZCL zone. The ZCL must have a corresponding ZCL end instruction, sooner or later. MCRs should NOT be overlapped with a ZCL. Overlapping MCRs and ZCLs result in unpredictable operation.

The difference between the ZCL and the MCR is that when false the ZCL freezes all the outputs in the zone, where the MCR when false turns off all outputs.

If I use subroutines to do what the ZCLs are doing here will the MCR command still kill the outputs within the subroutine?

 

[Skiroy]

You can use the any of the timer bits (EN, DN, TT) or the ACC value anywhere in the program, you could have more than 1 T4:0 timer but they would not work as you would expect them to, you are correct in saying you should have only 1 instance of the timer.

Well I now noticed that the duplicate timer are only within a seperate ZCL zone,which I understand a subroutine would act the same as a ZCL zone. So being that the same Timer address is being duplicated but only within a seperate subroutine should it act as I expect it and act the same as the old program?


I understand I shouldnt be trying to duplicate the program. BUt what I am trying to get out of this is to do my best to understand the program and duplicate it. Have it ready for when the hard ware gets here. So I can just tell the Boss straight up to let me download it and see if it works and maybe a day or 2 to get it to work. If it doesnt then bring in a contractor. Its not a rush situation.

 

[Lancie1]

So being that the same Timer address is being duplicated but only within a seperate subroutine should it act as I expect it and act the same as the old program?

I think it would act like the old program, but personally I have never tried that method, so I cannot say for sure. I have never run out of timers (in any PLC except some stripped-down unit like the Omron ZEN), so have found no need to reuse them. The old PLC2 was limited in memory and also in the number of timers (56 available timers without an expansion module), so it may have been necessary in some programs to reuse the same timers inside of separate subroutines or ZCL zones.

If I use subroutines to do what the ZCLs are doing here will the MCR command still kill the outputs within the subroutine?

EDIT: I see the PLC2 manual, Chapter 11, says NO, a MCR will NOT kill the outputs within the subroutine.

WARNING:

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Do not place a Label instruction in a ZCL or MCR zone. When jumping over a start fence, the processor will execute the program from the label to the end fence as if the start fence had been true, i.e., outputs controlled by the rungs. The start fence may have been false, intending that all outputs within the zone be controlled by the output override instruction, i.e., Off for MCR or last state for ZCL instructions (Section 7.1). Unpredictable machine operation and damage to equipment and/or personal injury could result. ​

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Most programmers get rid of MCRs whenever they can. MCRs are now used so sparsely that many of us tend to at first overlook them in the program. The problem is that where there are several MCR zones, it can be difficult to determine where each starts and stops. Each MCR begin and end rung should have a comment that numbers or otherwise identifies the MCR. Something like "MCR #2 Start", and later "MCR #2 End".

 

[Skiroy]

Thankx guys. I think I will try to re use the timers in the subroutines. If that causes issues I will use different ones. Im just not sure how they are connected. And like I said if I have a Timer EN or DN else where in the program Im not sure how that is linked to which duplictae timer in a ZCL zone elsewhere. And I will also start with the MCR and then move to a Start stop dummy bit. Or maybe do both.

I think I have enough understand to take the task on the best as I can and get from the experience as much as I can. If it works I will be excited but if not I am still greatfull for the whole process. I learned alot already. Thankx.

Im sure I will be back.

Thankx Again everyone.

 

[jrwb4gbm]

Did anyone ever get a copy of the plc2 program from the dropbox link in post #82?
Link:
http://www.plctalk.net/qanda/showpost.php?p=497139&postcount=82
I just cant seem to get the dropbox link to work. All I get is error 403 which is a picture saying I dont belong there. If someone did get a copy, would you either post it to the thread or upload it somewhere and PM me a link other than thru dropbox, I would appreciate it.

 

[curlyandshemp]

Did anyone ever get a copy of the plc2 program from the dropbox link in post #82?
Link:
http://www.plctalk.net/qanda/showpost.php?p=497139&postcount=82
I just cant seem to get the dropbox link to work. All I get is error 403 which is a picture saying I dont belong there. If someone did get a copy, would you either post it to the thread or upload it somewhere and PM me a link other than thru dropbox, I would appreciate it.

For access to a dropbox account you need a user name password and need to login

 

[jrwb4gbm]

For access to a dropbox account you need a user name password and need to login

Thanks for the info. I do have my own user name and password and even after logging in to my dropbox account, I cant download the file(s). Do I need the username and password of the poster of the link?

 

[The Plc Kid]

Thanks for the info. I do have my own user name and password and even after logging in to my dropbox account, I cant download the file(s). Do I need the username and password of the poster of the link?

It depends on how he is sharing it. He can create a link for open or password type sharing or he can put it in his public folder.

 

[jrwb4gbm]

It looks like it is in a public folder based on the link, but I could be wrong.

This is the link I was referring to.
https:// dl-web.dropbox.com/get/Public/Burroak%20Program.PDF?w=3ddf53fc

Anyway, it was worth a shot. Thanks everyone.

 

[Lancie1]

Jr, You better run your anti-virus software. What I got after going to that Dropbox link was a warning from my AVG Anti-Virus software that some malware had just been loaded on my computer. I had to dis-infect and delete about 9 files.

 

[jrwb4gbm]

Jr, You better run your anti-virus software. What I got after going to that Dropbox link was a warning from my AVG Anti-Virus software that some malware had just been loaded on my computer. I had to dis-infect and delete about 9 files.

Thanks for the info.

 

[Daniel_Brasil]

The program link posted by Skiroy is wrong. This is the correct address:

"http://dl.dropbox.com/u/96052065/Burroak Program.PDF"


best regards,
Daniel

 

[jrwb4gbm]

The program link posted by Skiroy is wrong. This is the correct address:

"http://dl.dropbox.com/u/96052065/Burroak Program.PDF"


best regards,
Daniel

Thank you for posting the correct link.

 

[Skiroy]

Hey guys. I just started to copy the program into my RS LOGIX 500 starter lite(free version). I want to see if someone can open my file in a regular RS LOGIX 500 version. We are supposed to get RS LOGIX 500 Starter(not free version) in a week. Im hopeing this file I posted will open without having to rewrite it again.

Can someone see if they can open it? I dont have any addressing because I still dont know what hardware we are getting.

http://dl.dropbox.com/u/96052065/BURROAK.RSS

Thankx

 

[Lancie1]

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