SLC500 Project Upgrade

Hello All,

I have been assigned to upgrade the automation system of a District Heating plant.
At present the system employs two SLC500 PLCs. The first PLC (image 1) does all the process and is connected to a Wonderware SCADA. The second PLC (image 2) is taking inputs and writes outputs from/to a mimic panel to the process PLC. The two PLCs communicate using DH485.
I dont know why it is done like that since the distance between the two PLCs is just 2m. IMO the mimic PLC could be a second rack of the control PLC.
It is know required to expand the system and add some equipment to the pumphouse, add a hot water storage facility and add a remote pumphouse for a small town a few km away.
It is decided that the equipment for the new installations (heat storage and new pumphouse) will be from Siemens. Also the VFDs at the existing plant will be either from ABB or Siemens.

We want to avoid rewiring all the existing AB equipment for the following reasons:
1. Save on equipment cost.
2. Save on labour cost.
3. It has been operating reliably for 10 years.

I am looking into a solution where I want to replace the two AB SLC500 CPUs and make them RIOs by adding some sort of interface using Ethernet.
I imagine it is not possible to use a Siemens CPU to read the two RIOs, so I am planning to use a ControlLogix CPU to Read the RIOs. What I also need from the ControlLogix CPU are the following:
1. Be able to connect to a WinCC Scada (I would prefer to avoid an OPC solution if there is the option of an Ethernet/IP driver in WinCC).
2. Be able to control VFDs using Profinet (We can live with Profibus-DP).
3. Be able to communicate with S7-300 / S7-1500 CPUs (not much is to be communicated between the AB and the Siemens PLCs, as the stations operate autonomously. The important thing is the connection of the stations to the SCADA).


Can you please share your comments and experiences on my setup?

Regards

This looks like a good place for the new 1747-AENTR. You replace the CPU in each SLC rack with this module and configure it to act as an Ethernet IP adapter for the existing I/O. Be wary of the high number of analog you have and how to count up the required connections or nodes to size your new CPU(s).

I am not experienced with profibus, but there are modules available for 1756 Chassis to make that part of the project feasible too. I can't help much with your other bullet points either, and don't have any first hand experience with the SLC adapter.

How long can this site be offline for? it's a pity it still looks so neat, because I'd be inclined to suggest replacing everything.

If you are working with Siemens for everything else, then it seems a little awkward sticking an AB here for I/O only.

Also the SLC is now "silver series", so you are probably not doing your client any favors by leaving in a semi-retired system. Don't get me wrong, they're brilliant PLCs (and I still have several!) but if you can tolerate an extended downtime then I'd say at least discuss with your client the full replacement option.

(and keep those I/O to sell at a hefty margin on E-bay in the next 5 years as rockwell run out of stock and everyone who hasn't upgraded goes into a mad panic).

Saffa said:

How long can this site be offline for? it's a pity it still looks so neat, because I'd be inclined to suggest replacing everything.

If you are working with Siemens for everything else, then it seems a little awkward sticking an AB here for I/O only.

Also the SLC is now "silver series", so you are probably not doing your client any favors by leaving in a semi-retired system. Don't get me wrong, they're brilliant PLCs (and I still have several!) but if you can tolerate an extended downtime then I'd say at least discuss with your client the full replacement option.

(and keep those I/O to sell at a hefty margin on E-bay in the next 5 years as rockwell run out of stock and everyone who hasn't upgraded goes into a mad panic).

Click to expand...

SST (Molex) made, at one time, a Profibus card which would replace the processor in a 1746 chassis, and make the chassis look like remote I/O to a Profibus master. I don't know if they still make them, but it would be a good choice here, since the OP seems O.K. with Siemens as a master. And, of course, all the I/O would remain, untouched.

There is enough offline for the site to do a complete replacement of the equipment.
I am just trying to find the most cost effective solution.

Jeffrey, could you provide a link for that SST module? I looked at their website but I only found Profibus-DP modules for the SLC500 Rack.

Regards.

I was in the same position as you a while back. Had a customer with 2 10-slot racks and wanted to secure them for the future, and was thinking about making RIO's out of them both, and replacing the CPU with a new one from ABB.
I found some 3rd party profibus-adapters just like mentioned here, and was also considering trying with ControlNET (mostly because it would be fun if it worked!).
But after thinking about it, I don't think that it's worth bothering making RIO's out of them. The I/O's might work fine for now, but they are still +10 years and will sooner or later be stopped manufactured. Ofcourse AB will still supply replacement parts for a very long time, but will the 3d party supplier do the same with the profibus-adapter?

I have made RIO's out of old ABB-systems, but the difference is that it's fully supported by ABB to integrate the old I/O's with the new CPU. Plug and play so to speak!

In my case I let the whole system be for now. The time comes when the customer wants to rebuild the system and get more functions, and that's when the hardware gets replaced.

If you have to put extra new hardware and make a special solution just to use the old hardware, then you should really just throw out the old hardware. That's my point of view atleast

Saffa said:

How long can this site be offline for? it's a pity it still looks so neat, because I'd be inclined to suggest replacing everything.

If you are working with Siemens for everything else, then it seems a little awkward sticking an AB here for I/O only.

Also the SLC is now "silver series", so you are probably not doing your client any favors by leaving in a semi-retired system. Don't get me wrong, they're brilliant PLCs (and I still have several!) but if you can tolerate an extended downtime then I'd say at least discuss with your client the full replacement option.

Click to expand...

Very few pieces of the SLC modular style stuff is silver, the RIO and Controlnet adapters being the most notable in my opinion. It is a mature product, yes, but is nowhere near obsolete.

http://www.rockwellautomation.com/r...ation-solutions/product-search/overview.page?

The silver page is new and improved...type in 1747 and 1746 for the part number searches.

If you use the more common types of SLC I/O, it will be supported for a long long time.

With that said, I do agree with updating it...perhaps just half of it, replace the main rack with the Logix5k controller so you get to keep your neat and spacious panel layout, and have half the I/O modernized. Seriously, it would not surprise me if the SLC I/O is still around and easy to find in 20 more years.

Thanks for the link OkiePC, I stand corrected. The local rep for AB gear must have confused me last time he was round. . Or maybe he was just dead keen to sell a few new compactLogix systems!