Replacing AB PLC2 with AB PLC5

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We want to replace a AB PLC2 with a new AB PLC5/60.

My first thought is rack compatiblity. What is the minimum series and verison that modern PLC's will work with? If it on AB's Knowledgebase or in the Enhanced Processor manual I missed it.

What are the other do's, don't's, watchchas, and/or gotchas (forgive the grammar)?????
 
Have a talk to your local AB rep. You may (will) find that a control logix conversion will be cheaper and far more powerful and flexible. Regards Alan Case
 
To switch or not to switch?

You did not say if you are going to change all of your I/O in addition to changing the processor. If you are changing out the complete PLC2 system, I/O and all, then Alan has a point about going to the Control Logix. If you are going to keep the old 1771 I/O system then changing to the PLC5 is not to big of a problem except for the program of course. You will have to re-write the program in PLC5 syntax which is a bit different than the old PLC2.
 
PLC/5 is on the way out now.
Hardware will still be available for quite some time, but support and pricing will not be with you for too much longer.

If I were doing a big upgrade like that I would go to control logix.
 
A few other items:

1. If you're keeping the 1771 I/O and it uses multiple local racks, they'll need to be changed over to remote racks - unless you've already got the PLC-2 type remote I/O distribution panel. This will involve the purchase and installation of new I/O adapter$ (or maybe check eBay).

2. You can go with Control Logix and still keep your existing I/O. See no. 1.

3. It's not often mentioned but, Softlogix could also be an option for you. Essentially the same instruction set and feel as a PLC-5 but on a PC platform. You didn't mention your processing needs but, Softlogix includes long integers and structures, which could make some things easier. See no. 1.
 
I've done many PLC-2 to PLC-5 and SLC-500 conversions. Here are the things to look out for.

I'm assuming that you've already got the 5/60 in hand so I won't recommend gong the CLX route.

1) The PLC-2 could communicate with multiple local racks. The 5 can do this too but unless the PLC-2 uses remote I/O you'll have to replace all of the adaptors except for the one in the local rack. The rack that you choose to be the local rack will contain the PLC-5.

2) The old rack power supplies are not compatible with the PLC-5 processor. If you intend on putting the PLC-5 in one of the existing racks you'll have to find an alternative way to power the rack. There are a couple of options.
a) If your existing system uses series a racks, wwap out the rack with a series B rack and use a P7 power supply or a slot power supply in one of the open slots
b) If you can free up the 1st slot you can keep your old rack and use a slot supply.

2) The PLC-2 started with rack 1, the PLC-5 starts with rack 0. There are a couple of solutions to this.
a) Add a new rack just for your PLC-5. Set it up so that it doesn't occupy more than 1 logical rack. The rest of the racks in your system will have the same (excluding the I and O instead of 1 and 0 at the start) addresses.
b) Put your PLC-5 in rack 1 and configure it to start at rack 1. The default is rack 0.

Now for some program issues.

3) The PLC-2 only had < and = instructions. This means that those confusing greater than logic rungs with the variable positions swapped will still be there in your translated code.

4) The PLC-2 had no constants either. You had to load memory addresses with the values you wanted to compare.

5) The conversion program doesn't make your program any more modern than it is. This means that all of the other drawbacks of PLC-2 code
will still be there. For example:
a) No one-shots
b) No compute instructions
c) No multiple outputs on the same rung
d) No parameter passing to subroutines
e) No For-Next loops
f) No AFI
etc...

Finally, if you're planning on using the conversion utility my recommendation is to use it to create a basis for your new program. Once converted, start dividing up your program into subroutines, combining rungs, adding one-shots, etc... In other words, PLC-5ate it.

If you've got any questions, don't hesitate to ask.

Good Luck,

(8{)} ( .)
 
WHY?


Why replace OLD, OLD, OLD Technology with OLDER Technology?



Unless your customer dictates it, look in to AutomationDirect's BRX line of PLC's. No I am not a salesmen for AutomationDirect. Just a frustrated and disgruntled AB user looking for and has found better alternatives and customer service. Their (AD's) High End CPU (for the BRX line) which cost less than $500, has Ethernet IP, Modbus TCP, Rs232, RS485, MicroSD slot and a second Ethernet port can be had for as little as $69. How much is it to convert a DF-1 Micrologix to a Sloooooooow Net-Eni Ethernet interface? About $1,000. The BRX Platform (high end unit), has on-board 20 discrete Inputs, 16 Discrete Outputs, 4 Analog Inputs, 2 Analog outputs. Programming Software is FREE, FREE, FREE, and guaranteed to be free. All firmware and software updates are free and you do not have to have a service contract or register and go thru time wasting hoops to get them. Add-on I/O modules are 1/10th the cost of AB's products if not less. This thing makes a high end Micrologix looks like a YUGO that needs its third engine rebuild before it can be push started. As far as Scan time goes, it makes Micrologix looks like a Yugo that hasn't got its engine installed yet. Dare I say this might even be equivalent to or better than the CompactLogix L43 platform costing more than $5,000 for the CPU alone. Sure, software can be a little quirky. As if Rockwell's stuff wasn't. Rockwell has been selling the same buggy garbage they had for decades re-rebranding them as FactoryTalk View or Studio this and Studio that. Thanks to Bill Gates for mastering the art of how to get your customers to pay to fix your own bugs while calling them updates. Brilliant. However, after you get familiar with the AD's Do-More software and Master the Math-box function, you will not utter the word Micrologix ever again. EVER. About now, I am starting to forget the word CompactLogix. Except of course for the customers that are willing to pay an arm and a leg to have it. And yes, I quote them two arms and two legs for my aggravation. They keep paying. Oh well. The misery continues.


But seriously,



Invest a little time to learn something new. Maybe you can upgrade the entire system for what you would pay just for the 5/60 CPU alone and ask your boss for a raise.



Sorry for the RANT.


Cheers.
 
I know this is old, but one thing you have to keep in mind is down time. A complete rip out/re-wire takes a lot of time, and Time is money.

the above statement By Ken holds true.

i have done many PLC2 to PLC5 conversions in the 1990's to 2000's
in 6200 series software on a DOS machine.

the deciding factor was available time to upgrade and since both systems are octal based, same I/O but with different adaptors. i simply just used a 4 slot rack for the PLC 5 and kept the PLC2 CPU bolted in, swapped adaptors and rack dip switch settings to suit.

it was a fairly simple (but very time consuming) migration with the added advantage of a fall back to PLC 2 if it went wrong.
 
Last edited:
WHY?


Why replace OLD, OLD, OLD Technology with OLDER Technology?



Unless your customer dictates it, look in to AutomationDirect's BRX line of PLC's. No I am not a salesmen for AutomationDirect. Just a frustrated and disgruntled AB user looking for and has found better alternatives and customer service. Their (AD's) High End CPU (for the BRX line) which cost less than $500, has Ethernet IP, Modbus TCP, Rs232, RS485, MicroSD slot and a second Ethernet port can be had for as little as $69. How much is it to convert a DF-1 Micrologix to a Sloooooooow Net-Eni Ethernet interface? About $1,000. The BRX Platform (high end unit), has on-board 20 discrete Inputs, 16 Discrete Outputs, 4 Analog Inputs, 2 Analog outputs. Programming Software is FREE, FREE, FREE, and guaranteed to be free. All firmware and software updates are free and you do not have to have a service contract or register and go thru time wasting hoops to get them. Add-on I/O modules are 1/10th the cost of AB's products if not less. This thing makes a high end Micrologix looks like a YUGO that needs its third engine rebuild before it can be push started. As far as Scan time goes, it makes Micrologix looks like a Yugo that hasn't got its engine installed yet. Dare I say this might even be equivalent to or better than the CompactLogix L43 platform costing more than $5,000 for the CPU alone. Sure, software can be a little quirky. As if Rockwell's stuff wasn't. Rockwell has been selling the same buggy garbage they had for decades re-rebranding them as FactoryTalk View or Studio this and Studio that. Thanks to Bill Gates for mastering the art of how to get your customers to pay to fix your own bugs while calling them updates. Brilliant. However, after you get familiar with the AD's Do-More software and Master the Math-box function, you will not utter the word Micrologix ever again. EVER. About now, I am starting to forget the word CompactLogix. Except of course for the customers that are willing to pay an arm and a leg to have it. And yes, I quote them two arms and two legs for my aggravation. They keep paying. Oh well. The misery continues.


But seriously,



Invest a little time to learn something new. Maybe you can upgrade the entire system for what you would pay just for the 5/60 CPU alone and ask your boss for a raise.



Sorry for the RANT.


Cheers.

I was thinking the same thing... but more along the lines of just saying "Why replace outdated technology with other outdated technology?"
 
This thread was two years old when you joined PLCS.net


WHY?


Why replace OLD, OLD, OLD Technology with OLDER Technology?



Unless your customer dictates it, look in to AutomationDirect's BRX line of PLC's. No I am not a salesmen for AutomationDirect. Just a frustrated and disgruntled AB user looking for and has found better alternatives and customer service. Their (AD's) High End CPU (for the BRX line) which cost less than $500, has Ethernet IP, Modbus TCP, Rs232, RS485, MicroSD slot and a second Ethernet port can be had for as little as $69. How much is it to convert a DF-1 Micrologix to a Sloooooooow Net-Eni Ethernet interface? About $1,000. The BRX Platform (high end unit), has on-board 20 discrete Inputs, 16 Discrete Outputs, 4 Analog Inputs, 2 Analog outputs. Programming Software is FREE, FREE, FREE, and guaranteed to be free. All firmware and software updates are free and you do not have to have a service contract or register and go thru time wasting hoops to get them. Add-on I/O modules are 1/10th the cost of AB's products if not less. This thing makes a high end Micrologix looks like a YUGO that needs its third engine rebuild before it can be push started. As far as Scan time goes, it makes Micrologix looks like a Yugo that hasn't got its engine installed yet. Dare I say this might even be equivalent to or better than the CompactLogix L43 platform costing more than $5,000 for the CPU alone. Sure, software can be a little quirky. As if Rockwell's stuff wasn't. Rockwell has been selling the same buggy garbage they had for decades re-rebranding them as FactoryTalk View or Studio this and Studio that. Thanks to Bill Gates for mastering the art of how to get your customers to pay to fix your own bugs while calling them updates. Brilliant. However, after you get familiar with the AD's Do-More software and Master the Math-box function, you will not utter the word Micrologix ever again. EVER. About now, I am starting to forget the word CompactLogix. Except of course for the customers that are willing to pay an arm and a leg to have it. And yes, I quote them two arms and two legs for my aggravation. They keep paying. Oh well. The misery continues.


But seriously,



Invest a little time to learn something new. Maybe you can upgrade the entire system for what you would pay just for the 5/60 CPU alone and ask your boss for a raise.



Sorry for the RANT.


Cheers.
 

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