RSLinx Classic vs FactoryTalk Linx: which one do you need?

Somebody flips Studio 5000 over to FactoryTalk Linx (it's one menu item since V31), and the controller that sat in Who Active yesterday is gone. Nothing broke. FactoryTalk Linx keeps its own drivers in its own Network Browser, and the ones you built in RSLinx Classic aren't there. I've sorted out that exact mix-up more times than I'd like. Below is how the two programs split the work, which RSLinx Classic edition fits your job, and what to check when a PLC answers ping but won't show up anywhere.

The short version

RSLinx Classic is Rockwell's original communication server. It holds the drivers and runs RSWho, and it's the OPC DA and DDE server for anything else that wants PLC data. RSLogix 5 and RSLogix 500 go online only through it, and so does every Logix Designer older than V31.

What used to be RSLinx Enterprise is now FactoryTalk Linx. It's the data server for FactoryTalk software such as View SE and ME, it comes with the FactoryTalk Services Platform, and it's optimized for Logix controllers. Its driver list is narrower.

Classic itself was never replaced. Rockwell renamed the other product, and the near-identical names have confused people ever since. Both run fine on one PC, and on most engineering laptops I touch, both are already there.

My rule of thumb:

·       SLC 500, MicroLogix, PLC-5, or a Logix project on V30 and older: Classic.

·       Screens in FactoryTalk View: FactoryTalk Linx.

·       A third-party app wants OPC DA or DDE: a paid Classic edition, or FactoryTalk Linx Gateway.

·       Logix Designer V31 and newer: either one. Communications > Select Communication Software decides.

Which RSLinx Classic edition you actually need

There are four editions now: Lite, Single Node, OEM and Gateway. Older write-ups mention Professional, but it's not in the current lineup. The edition comes from the activation on the PC. Start the software without a valid one and it runs as Lite.

Edition	OPC and DDE	Devices served to OPC/DDE	OPC clients on other PCs	Cost
Lite	No	None	No	Free, comes with the programming software
Single Node	Yes	One	No	Paid activation
OEM	Yes	Any number	No	Paid activation
Gateway	Yes	Any number	Yes	Paid activation

 

Lite covers everything a programming laptop needs: go online, upload, download, flash firmware with ControlFLASH. No OPC, no DDE, no API. The day a historian or an Excel sheet wants live tags, Lite is done.

Activations run through FactoryTalk Activation on anything from 2.58 up. Lose the activation and you get a seven-day grace period, then the software drops back to Lite. The warnings land in the FactoryTalk Diagnostics log every four hours, which nobody on night shift reads. Programming keeps working, the OPC client on the line stops getting data, and that's usually how people find out.

OPC, DDE and the Gateway question

Single Node and OEM serve OPC clients on the same PC only. A client reaching in from another machine needs Gateway. And Classic is an OPC DA server, not OPC UA.

For UA, or for data that already lives in FactoryTalk, there's FactoryTalk Linx Gateway. Separate product, not a Classic edition. It hands FactoryTalk Linx data to OPC DA, OPC UA, MQTT, DDE and Excel (RTD) clients, and its activations are sized by tag count: Basic 1,000, Standard 5,000, Extended 15,000, Distributed 32,000. Professional isn't unlimited, though. It defaults to 500,000 OPC UA tags.

RSLinx Classic or FactoryTalk Linx: who talks through what

Who uses RSLinx Classic, who uses FactoryTalk Linx, and the one port they fight over.

Task	RSLinx Classic	FactoryTalk Linx
RSLogix 5, RSLogix 500	Yes, the only option	No
Logix Designer V30 and older	Yes	No
Logix Designer V31 and newer	Yes	Yes
FactoryTalk View SE / ME	Possible as an OPC/DDE server (not Lite), but not needed for Rockwell controllers	Yes, the usual pick
Third-party OPC DA / DDE clients	Single Node, OEM, Gateway	Through FactoryTalk Linx Gateway
Changing 1756-ENET configuration	Yes	No
Device that stopped answering	Stays in RSWho with a red X	Drops out of the browse
Boolean read into an integer	0 or 1	0 or -1
Named path to the data	DDE/OPC topic, shared by every app	Device shortcut, separate per application

 

Running both on one PC is normal. These are the catches I check first:

·       Port 44818. Only one program on the PC can hold TCP 44818 for unsolicited messages. FactoryTalk Linx takes it only when "Listen on EtherNet/IP encapsulated ports" is ticked in its Ethernet driver's advanced settings. If Classic or KEPServerEX needs unsolicited messages on that machine, leave that box unticked.

·       The UDP checkbox. Since 4.10, "Accept UDP Messages on Ethernet Port" in Classic is off by default, which leaves 44818 to FactoryTalk Linx and CIP Security. Need it back? Free the port first by turning off "Listen on EtherNet/IP encapsulated ports" in the FactoryTalk Linx Ethernet driver's advanced settings, then check the box under DDE/OPC > Options > General.

·       Serial ports. One COM port, one owner. When both programs need the same DF1 port, configure it in FactoryTalk Linx and share that driver with Classic. A dual-channel 1784-PKTXD splits instead: channel 1 goes to FactoryTalk Linx, channel 2 to Classic.

·       Install drive. Put FactoryTalk Linx on the same drive as Classic, or its icons turn into question marks.

Who Active in Logix Designer browses through whichever program is picked under Select Communication Software. Close the project before you switch.

One more for anyone running a 5380 or 5580. Since v32 firmware those controllers have unsigned and 64-bit types, and Classic can't read LREAL, UDINT, ULINT, UINT, USINT, TIME, LTIME, TIME32, LDT or DT. Tags of those types don't show up in the FactoryTalk Live Data tag browser, and any access to them returns an error. Check the data type before you blame the HMI.

RSLinx Classic doesn't see the PLC, but ping works

The order I go through when a PLC answers ping but won't show up.

Ping answering proves the IP stack and nothing else. RSWho needs the right driver and, for a browse, a broadcast that really gets to the device. Most "RSLinx can't see my PLC" cases I get land in one of these:

1.    RSWho sees it, Studio 5000 doesn't. Logix Designer is pointed at the other program, so look at the Select Communication Software setting. Takes ten seconds, so it goes first.

2.    Another subnet. A remote subnet browse with the EtherNet/IP driver works only if directed broadcast is enabled on every router interface connected to that remote subnet (an ACL can limit that to port 44818). In most plants I wouldn't count on it. Add the device by IP instead.

3.    Old Ethernet hardware. The original 1756-ENET is the module I see missing from a browse most often, and even the FactoryTalk Linx Network Browser can't discover it. In Classic, add an Ethernet devices driver, turn Address Mapping on and type the module's IP in as a station. That driver was built for PLC-5, SLC 5 and ControlLogix Ethernet ports anyway. On the FactoryTalk Linx side, add the 1756-ENET as an offline device in FactoryTalk Administration Console.

4.    Behind a bridge. For a device on an Ethernet bus under a bridge module, right-click that bus in RSWho, open Properties and type the address into Manual Address Entry.

5.    The icon. A red X means Classic saw the device before and it stopped answering: power, cable, or somebody changed the IP. A yellow question mark, usually with "Unrecognized Device" next to it, means the EDS file for that device and firmware isn't registered. Version 4.60 fixed automatic EDS upload for some devices, PowerFlex drives among them.

6.    Nothing at all, same subnet. Say the laptop has Wi-Fi, a USB Ethernet dongle and a VM adapter. Check which adapter and IP address the EtherNet/IP driver is set to in its configuration. Browse and ping don't have to go out the same door.

Drivers and the hardware behind them

Old interface hardware is the real reason RSLinx Classic still lives on my laptop. Here is what each common piece needs in Classic:

Hardware	What it connects	Driver in Classic
1756-ENBT, 1756-EN2T	ControlLogix on EtherNet/IP	EtherNet/IP driver, browses the subnet
1756-ENET	First-generation ControlLogix Ethernet, 10 Mbps	Ethernet devices driver, IP mapped to a station
1747-UIC	PC USB to DH-485: SLC 500, DH-485 MicroLogix, PanelView Standard	DH485 UIC driver
1784-U2DHP	PC USB to DH+	1784-U2DHP driver for DH+
1784-PKTX	PCI card for DH+ or DH-485	1784-PKTX(D)/PCMK driver
1784-PCMK (in the 1784-PCMC kit)	Laptop PCMCIA card for DH+ or DH-485	1784-PKTX(D)/PCMK driver
1761-CBL-PM02	RS-232 to the 8-pin mini-DIN port on a MicroLogix	RS-232 DF1 devices driver

 

1747-UIC: USB on one end, DH-485 on the other. In Classic it runs on the DH485 UIC driver.

Before you plug a cable straight into a MicroLogix or SLC serial port, check what that channel is set to. A channel set to DH-485 won't answer a DF1 driver, and the other way around. Same cable, same port, nothing in RSWho. The 1747-UIC is the exception: it translates, so the PC can use the DH485 UIC driver (or the RS-232 DF1 devices driver at 19200 baud) while the controller channel stays on DH-485.

Windows 11, versions and the 2026 security fix

Check	What to know
Version to be on	4.60.00 or newer (4.60.00 came out in September 2025)
Windows 11, Server 2025	Supported by 4.60
Windows 10 Pro and Enterprise	The 4.60 installer refuses them after April 14, 2026. The LTSC builds are still on the list
Logix Designer	4.60 works with V38 and older
RSNetWorx	9.00 or older has to be upgraded before 4.60 goes on
VBScript	Needed by every installer up to Classic 4.60.00 and FactoryTalk Linx 6.60.00
Security	4.50 and older carry four denial-of-service flaws, fixed in 4.60

 

The VBScript one catches people on fresh Windows images. In Windows 11 24H2 VBScript is an optional feature that's on by default, but Microsoft plans to switch it off by default around 2027, and a stripped corporate image may not have it at all. If setup dies halfway, go to Settings > System > Optional features > View features, search for VBScript, install it and reboot. Rockwell is moving its installers off VBScript with releases from fall 2026 on.

On September 1, 2026, four denial-of-service flaws were published for RSLinx Classic 4.50 and older: CVE-2026-9621, CVE-2026-9622, CVE-2026-9624 and CVE-2026-9625. A crafted CIP packet crashes the service, and it stays down until somebody restarts it. On a Gateway PC that a whole line pulls OPC data through, that's downtime, not a nuisance. Can't upgrade this week? Then keep that PC off every network it doesn't strictly need.

FAQ

Is RSLinx Classic free?

Lite is. It's a free download, and every Rockwell programming package includes it. Going online, uploads, downloads and firmware flashing all work, but there's no OPC and no DDE. Single Node, OEM and Gateway are paid activations.

What replaced RSLinx?

Nothing replaced RSLinx Classic. RSLinx Enterprise was renamed FactoryTalk Linx, and Classic is still maintained. Plenty of work still needs it, starting with RSLogix 500.

Why isn't RSLinx Classic launching?

Usually it is running, just as a service, which is the default. Start it from the menu and you get a prompt to stop the service. For a normal window: RSLinx Classic Launch Control Panel, Stop, clear "Always Run As Service", Start. Stopping the service interrupts traffic and can hit other software on that PC that uses it, so don't do it on a live Gateway box mid-shift. If it never installed in the first place, check VBScript.

Is RSLinx Classic supported on Windows 11?

Yes. 4.40 already listed Windows 11, and 4.60 lists Server 2025 and the Windows 11 IoT Enterprise 2024 LTSC build.

Is FactoryTalk Linx an OPC server?

Not for outside clients on its own. Third-party OPC DA and OPC UA clients get FactoryTalk Linx data through FactoryTalk Linx Gateway.

Hardware that still runs through RSLinx Classic

Most of the interface hardware in that driver table is old, and that's exactly what IQElectro keeps on the shelf: the 1747-UIC and 1784-U2DHP for DH-485 and DH+, the 1784-PKTX card and the 1784-PCMC kit for older PCs and laptops, the 1761-CBL-PM02 serial cable, plus 1756-ENET, 1756-ENBT and 1756-EN2T modules. IQElectro covers them with its own 2-year warranty. The RSLinx Classic activation itself comes from Rockwell, we don't sell software licenses.