Plc Upgrade

[Guest Luis Ferrigno]

I have a machine with two old PLC's, a AB PLC 2 talking serial to a PLC 3. I want to replace them. I have a PLC 5/60, a PLC 504 and Logix 5561. What would be the best way to replace them. Also use Ethernet or DH+ and I need to use Block transfer. Thanks for any help I can get. Luis Ferrigno

[Ken Moore 23]

Can you provide a few more details? How many discrete I/O, analog? Remote chassis'? HMI?

[TConnolly 13]

Also please clarify what you mean by "the best way" The Logix 5561 is by far the most capable and newest of the PLCs you listed. But best way does not always mean 'best equipment.' Best way might mean most economical way, or it might mean the easiest way, or the least intrusive way, or the way to do it with minimal process interruption.

[gravitar 3]

I would have to say the "easiest" upgrade would be to put the PLC-5 in place of the PLC-2 local adapter (or the proc. itself if it is a Mini) and go that route. There's even a software package to help convert the code. Once you've got the machine running from the PLC-5, you'll have DH+ comms built in and you can choose to upgrade to an Ethernet PLC-5 if you decide that ethernet is the way you need to go. but like other have said, going the ControlLogix route might make more sense depending on the circumstances.

[BobLfoot 301]

You don't mention distances between the PLC2 and PLC 3 but you might want to consider the following. Use the Logix 5561 along with a 1756-ENBT and 1756-CNB and replace the PLC 2 CPU with a 1771-ACN and the PLC 3 CPU with a 1771-ACN. This will mean rewriting all your PLC2 and PLC3 code to controllogix but will get all you code in one CPU. You'll have to watch out for any 1771 analog io. You might want to use 1771-ASB and 1756 DHRIO if there is a lot of Analog in either the PLC2 or PLC 3 racks.

[Sanif 0]

I've done some PLC2/30 upgrades and I can share some insight to what I've done: 1. I removed the PLC2 and replaced it with a 1771-ASB, effectively making that chassis a remote i/o chassis. I hooked the RIO bus to a nearby PLC5. Dip switches on the backplane have to be set as well. 2. Using a Rockwell Software, I converted the PLC2 ladder to RSLogix 5. Conversion was simple and straighforward. 3. Point to note: TON and TOF in PLC2 have 3 time base 0.01,0.1 and 1 sec. In PLC5, only 2 time base, 0.01 and 1. It can create a bit of a problem, timing wise, if you are not careful. 4. PLC2 doesn't start with Rack 0, so the first rack is Rack 1. After conversion, that rack is still Rack 1. My PLC5 has already a Rack 1, so I have to change the configuration for the PLC2 chassis to Rack 10 ( Rack 1 thru 7 was taken) or some other rack higher than 1. 5. The converted PLC2 logic was added as a ladder file in the PLC5 logic. To convert PLC2 to ControlLogix, you can use the translate tool in RSLogix5000 to convert from RSLogix5. I've done this before, but have not commissioned the code. So I can't tell if it is working according to the original logic. For PLC3 to ControlLogix, from what I've heard, is a bit more tricky. My colleagues told me there isn't a conversion software available. However, Rockwell in US can do the conversion, for a fee, of course. Just sharing my experience. Cheers.

[jstolaruk 9]

IIRC, last Rockwell quote I got for PLC-2 to PLC-5 conversion was a flat rate of $800 just to run the software on it, then as an option $1/rung to check it.

[Jamie571 0]

I have done this exact thing on at least four different occasions. But watch out some of the older series racks will not support the ASB. They have a weird power plug on them and the top of the slot has a flip down flap for each card position. I normally put the PLC 5 in a 4 slot rack and when you use the ASB you may have to remove the power supply on the rack, if thats the case you'll have to buy a slot power supply. Its been about 6 years ago since my last upgrade to a PLC 5 because of the high cost of the processor and the low cost of SLC and compact logix hardware.

[bjclem 0]

I do plc2 to plc5 or clx all the time if you do not have the conversion software best way is call tech support at 440 646-5800 and let them convert it for you price is $1 rung for the basic conversion .