PLC-2 project given a go. OH NO!

Skiroy

Member
Join Date
Mar 2012
Location
Panama City,fl
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Okay guys. we have a very old machine that uses PLC-2 software. This machine was basically donated from the other company in Tennesse. It came with the Program wiped out and no back up. Then the guys that worked here fried the PLC. So they got a new PLC and I/O units and the software and want me to get it running. The problem is I only know RSLogix 500. So this thread is probably going to save my life as the more I look into it PLC-2 programming is very different even though I have a couple weeks to prepare before the parts make it here. And they are buying the non AB PLC-2 that is written to use with Windows so I have no idea what it looks like and really hope its GUI friendly like RS Logix 500.

By the way the only thing I have to work with is the print out of the program that came with the machine's manual and it looks very similar as far as rung based ladder logic but the addressing looks weird.


Let me fire off by asking this before I get knee deep into things.

1. I was read that PLC 5 addressing is octal assigned. Is the PLC-2 the same or can some talk about this?

2. What about having to set the I/O module dip switches?

Bear with me guys and thankx so much for your help.
 
They bought new PLC-2 modules and software !?!?!?!

The circumstances you describe tells me that the machine is a prime candidate for scrapping the PLC-2 and starting all over with a new PLC. Since you know RSLogix 500 well, an SLC500 or ML1400 if the i/o no is not so high could probably do the job. The printed program listing will be enough for you to convert to RSLogix 500.

"They" are buying this stuff without discussing with you first how to solve the task. Stupid stupid stupid.
If I were in your shoes I would tell them to forget making a "new" PLC-2 program, no matter that they have already sunken money into that.
 
I agree with Jesper 100% forget the PLC-2 and put at least SLC hardware in if not the up to date Logix Platform.

A I/O count will help better determine what you need.

It would be pure stupidity to put a PLC-2 in equipment aimed at running full production.

IMO if you can't change their minds then this is the type of job you want to pass up and never look back.

Some customers are boat anchors and when you spot that you have to cut them loose before they make you sink with them.
 
I agree 1000%.

it will cost the company more for you to learn the plc 2 software, writing the program, and debugging the software than it will for you to start from scratch. if you/they do not have a tech contract, it will be a bigger mess.

you are correct, plc2 and 5 uses an octal addressing system.
questions for you to find out.
plc type, rack type, remote racks, addressing scheme?
as far as addressing type, if its remote i/o racks - is it complementary i/o. is the remainder of the racks 1/2 slot, full slot, double slot addressing? see the main plc rack for dip switch settings.

also, in the plc2, there are no designated timers, counters, bits like you are used to. add to this, you can use unused i/o points as timers, relays, counters.

i still have my plc2 books that i still use occassionally.

its a lot for you to comprehend, especially if you are used to logix 500.

good luck,
james


i would go with the slc 500 if possible.
 
Just came to think of something that may be important argument to NOT take this job.

Since it has (had ?) a PLC-2, the machine is probably around 20 years old, and therefore far from up to current safety standards. Can a risk assessment be found for example ?
Now, it can be acceptable to upgrade only the PLC for an existing machine if it stays in the same location and no change is done to its functionality or safety (no new functions however tempting !). Only in that case may the machine be allowed to run even if it is not up to current standard.
But when a machine is moved from one location to another, it must be up to current standards at the new location !.
You must be absolutely sure that you do not become responsible for this unless you are up to it.
I know that the PLC is not directly related to this, but if there is an accident the finger may point towards you because you touched the machine.
 
Use the 1771 rack, but replace the processor with a ControlNet adapter and add either a 1769 or 1756 processor rack with ControlNet. You will save the equipment dollars just in your time to program and maintain this beast.
 
As far as the PLC/2 software goes,read this link http://forums.mrplc.com/index.php?showtopic=12598&view=findpost&p=61720 for a review of the software.

If you cannot convince your nemesis to forgo the PLC/2 route and go with an ML1400 then you can still get all the PLC/2 manuals from the AB literature library on the AB website. The manuals will tell you how to address and configure the modules. There are several detailed threads on the forum that cover PLC/5 addressing, you may want to do a search and review those.
 
I agree that attempting to re-commission a PLC-2 based control system is both commercially and technically risky. CPUs and PLC-2 specific power supplies are all going to be over 20 years old, although because the PLC-5 extended the 1771 I/O platform, some of the I/O modules could be purchased new.

When you inevitably have a hardware failure, the parts are just going to become more rare and expensive.

My approach would be similar to those mentioned here: I'd try to get a 1771-ASB RIO adapter module for the I/O rack, and add an SLC-5/05 with 1747-SN RIO Scanner to the system to be the controller.

For the purposes of the Forum discussion, I'd like you to take a detailed inventory of module part numbers and revisions, and maybe some photographs.

The first reason is to make sure that the third-party PLC-2 software will work with your model of CPU. Some of the software I've seen only works with specific models.

The second reason is to determine if the hardware you have can be used with a RIO Adapter. Some PLC-2 era chassis and power supplies won't support the modern network adapters or power supplies.
 
Depending on the size and complexity of the equipment, the Control system cost is often a small percentage of the total cost. Even if you can use the old I/O, it would probably be better to replace the I/O with new also. The rack and 8 pt I/O cards are often obsolete too with many years of wear and tear on them. If this really is an important machine, replace everyting on the PLC2
 
This machine was basically donated from the other company in Tennesse.
Ah-hah! Hillbilly logic! I know it well - I are one. :ROFLMAO: If a mule will carry the load, why buy a truck?

They still use Tennessee mules on the descent into the Grand Canyon, so I guess the old methods still work in some cases.

Hmmm...PLC2 from a Tennessee plant? Did the old PLC have the spare key in a Bruton's Snuff tin scewed to the left side of the rack?
 
Last edited:
Ah-hah! Hillbilly logic! I know it well - I are one. :ROFLMAO: If a mule will carry the load, why buy a truck?

They still use Tennessee mules on the descent into the Grand Canyon, so I guess the old methods still work in some cases.

Hmmm...PLC2 from a Tennessee plant? Did the old PLC have the spare key in a Bruton's Snuff tin scewed to the left side of the rack?
Sounds to me like the boys in Tennessee might have bought the truck after all and then just kept the mule around until the Adopt-A-Worn-Out-Mule day came around.
 
:ROFLMAO: Steve, that is probably what happened - the Tennessee bumpkins traded off the old mule to some place that didn't know it was old and worn-out!
 
"Yessiree, we got a good deal for ya right here. See here? Go ahead, take a look at that swayed back right there - now that's the sign of a workin' mule right there, yessiree. And slow? Why shore he is - the slower the better, that's what I always say. You can take that to the bank. No foolin'. Fine mule that one is. Yep."
 
Everyone is on the money. Unfortunately,Convincing these guys of anything is a LOST cause. Im not going to waste my breath on the attempt. They will do what they want.

So this software does not utilize visual symbols to drag and drop on arung and then enter the addressing link RS Logix 500. And though I am okay on Rs Logix 500 I am not good enough to rewrite this program in a new language. Thats why I thought it would be easier to just visual copy everything I see in the print out.

So this is not the case?
 
Since it looks like there is no way to avoid this project, try to make an electronic copy of the manual and printout to post here in the forum. That would be a big help toward helping you.
 

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