Legacy PLC migration: S7-300, PLC-5 and SLC 500
Siemens moved the S7-300 to spares-only on Oct 1, 2025. Rockwell discontinued the remaining PLC-5 processors in 2017 and lists several SLC 500 controllers as discontinued. If your lines still run on them, the question is when you migrate, not whether.
We start with an audit that tells you where you stand: what controllers you have, how exposed each line is if a card fails, and a staged plan to migrate during planned downtime, with a fallback to the old rack if anything goes sideways.
Send an RFQ · Office: (877) 524-6674 · Line down? (877) 790-4697, 24/7, subject to personnel availability
- Spares onlySiemens S7-300 and ET 200M have been spare parts only since October 1, 2025.
- DiscontinuedRockwell discontinued the remaining PLC-5 processors in 2017. RSLogix 5 reached the end of its life cycle at the end of 2025.
- Partly discontinuedRockwell lists several SLC 500 processors as discontinued and points new systems at CompactLogix.
What we migrate
- Siemens S7-300 to S7-1500 / TIA Portal (and Step 5 to TIA Portal)
- Allen-Bradley PLC-5 to ControlLogix
- Allen-Bradley SLC 500 to CompactLogix
- HMI moves along with the PLC where it makes sense (WinCC, FactoryTalk View, Ignition)
What the audit gives you
- An inventory of legacy controllers, line by line
- Spares risk for each: if it died tonight, is there one on the shelf?
- A staged migration plan sized to your shutdown windows
- A fallback plan so you can return to the old rack if needed
The plan is yours. If you want us to do the work, we quote it from the hours it actually takes.
How the cutover works
- We back up and document what is running today.
- We convert and rewrite the program, then test it before the window.
- We cut over on site during your outage, with the old hardware ready to go back in.
- We prove it with your operators before we leave.
See also: Outage-window planning · Program backup and version control
Modeled best case
A best-case model, not a measured result.
Modeled area: four lines on S7-300, PLC-5 and SLC 500, audited first, then migrated one line per planned outage.
Lines with no spare CPU on the shelf (of 4)
Before: 3After: 0
Each migrated line runs on a current CPU, with a spare stocked for it.
Lines with no verified backup (of 4)
Before: 2After: 0
Each cutover ends with the backups brought up to date, so every line ends with a backup that matches what is running.
Unplanned controls downtime, per month
Before: 9 hAfter: 1 h
Aging racks and cards come out one line at a time, so fewer failures stop a line between outages.
Illustrative figures for the line, cell or area described, when everything goes right. They are not measured, not from any plant we have supported, not typical, and not a promise. A real job starts from your own baseline.
Send the platform, the symptom, and your outage window.
Use the quote form below or email sales@ts-controls.com. Office: (877) 524-6674. Line down right now? Call (877) 790-4697, 24/7, subject to personnel availability. We come back with a plan, not a brochure.
Straight answers
Questions we get.
Do we have to migrate everything at once?
No. You can go line by line, starting with the most exposed one.
Can you work with our existing code if nobody here wrote it?
Yes. We read what is running, document it, and convert it. Messy legacy code is normal.
What if the new system has a problem on startup?
That is why every plan has a fallback to the old rack until the new one is proven.
Do you come on site?
Yes. Evaluations happen at the machine so the first trip is not a guessing trip.
Request a quote
Find out where your controllers stand.
Send the plant, the controllers on each line, and your next shutdown. We come back with an audit plan, not a brochure.
Line down? (877) 790-469724/7, subject to personnel availability. How line-down support works.
Planning work? Office: (877) 524-6674Related