Trouble connecting to AB PLC - overlooking something?

I have a new job programming PLCs and HMIs after being away from them for ~7 years. I am trying to establish a test setup with an old AB ControlLogix 5561 that was lying around. I have tried every trick I remember in the book, but I just can't seem to connect!

I am physically connected directly to this PLC via an RS-232 cable, and directly via an Ethernet cable.

A) I am able to see the processor, backplane, and other cards in RSLinx Classic via when connecting direct to it via RS-232 to RS-232->USB adapter. However, when I try to go online, upload, or download to the PLC in RSLogix 5000, the application seems to time out ("Connecting to controller..." for about a minute, followed by "Failed to connect to controller. Can't communicate with RSLinx." - which is a strange message to get).

B) I can ping the PLC (via 1756-ENBT rev A). We're on the same subnet. A gateway is not present when I'm connected to it (since I'm directly connected), but I don't think it matters as the PLC is setup with a static IP. I have tried the Ethernet driver (which I admit I forgot how to use exactly) and the Ethernet/IP driver, and it browses forever.

Desperate questions/suspicions that I can't/haven't verified:

1) Do I need a 'null modem'?
2) Are some sort of ports being blocked?
3) Are all of the various bits of software and hardware's firmware revisions compatible/up to date?
4) I'm on the grace period for RSLogix 5000 right now - does this reduce functionality in any way?
5) Could any sort of PLC fault be causing this?

Why can't I connect? What else can I try? This seems like it should be simple, have I overlooked something? Please help, my confidence in this new job will be at rock bottom soon.

Welcome!

1. You can make your own cable if you have DB-9 solder cups
2-3
3-2
5-5

2. Could be, turn your firewall off temporarily

3. Check in RsLinx what firmware is loaded in the PLC, you need the same major firmware to match in L5K. Right click the processor and properties from memory

4. No, you can upload/download in grace

5. Possibly, but not likely both a serial and ethernet card faulty simultaneously

the_msp said:

Welcome!

Click to expand...

Thank you!

the_msp said:

1. You can make your own cable if you have DB-9 solder cups

Click to expand...

I'll keep that in mind and make one if I can find a connector.

the_msp said:

2. Could be, turn your firewall off temporarily

Click to expand...

Turns out I don't have permission even with admin... I'll get with IT.

the_msp said:

3. Check in RsLinx what firmware is loaded in the PLC, you need the same major firmware to match in L5K. Right click the processor and properties from memory

Click to expand...

Same major rev (17), but Linx shows that the processor is one minor rev above what I can select in RSLogix 5000, hmm...

the_msp said:

4. No, you can upload/download in grace
5. Possibly, but not likely both a serial and ethernet card faulty simultaneously

Click to expand...

OK.

Additionally, you said you could ping it, you can view this thread:

http://www.plctalk.net/qanda/showthread.php?t=127752&highlight=telnet

to see if the ports are open to you

the_msp said:

Additionally, you said you could ping it, you can view this thread:

http://www.plctalk.net/qanda/showthread.php?t=127752&highlight=telnet

to see if the ports are open to you

Click to expand...

Great link, thanks. Used TCPing and ports 80 and 44818 are open to me. Am I right in assuming that this implies a firewall block? Or would a firewall mean that I wouldn't get a response from the port?

twosixtyseven said:

B) I can ping the PLC (via 1756-ENBT rev A). We're on the same subnet. A gateway is not present when I'm connected to it (since I'm directly connected), but I don't think it matters as the PLC is setup with a static IP. I have tried the Ethernet driver (which I admit I forgot how to use exactly) and the Ethernet/IP driver, and it browses forever.

Click to expand...

I recommend verifying connectivity through the ENBT. To configure the Ethernet driver in RS-Linx, which it sounds like you have already added, select Communication from the main menu, and then Configure Drivers... from the drop-down. Double-click on the instance of the Ethernet driver, which by default will be named AB ETH-1.

Then, in the Station Mapping window, enter the IP address of the ENBT in one of the entries. Click OK and close out of the setup. Next, browse for that Ethernet module in RS-Who (Communications -> RS Who). Click on the Ethernet instance (e.g., AB ETH-1) and wait for the ENBT to appear. This does not happen immediately. Sometimes I turn off Autobrowse and manually browse multiple times until a newly added device shows up.

Assuming the ENBT shows up without a red X, or yellow ?, drill down to the processor as you described earlier. Right-click and attempt to get Device Properties. It should respond shortly with processor information, particularly the revision information. You must have the RS-Logix version installed on your PC for the processor revision.

If you can get this far, and have the correct software, and still unable to connect, I would question something about the processor -- maybe lying around because it was faulty. Someone with more knowledge about protection strategies may comment if there is a configuration setting that can prevent connections when the processor is definitely responding in RS-Linx.

twosixtyseven said:

Great link, thanks. Used TCPing and ports 80 and 44818 are open to me. Am I right in assuming that this implies a firewall block? Or would a firewall mean that I wouldn't get a response from the port?

Click to expand...

No, that would suggest they are open. Port 80 is the web port, so you can try typing that (the IP) into a web browser and see if it opens a status page.

Mispeld said:

Then, in the Station Mapping window, enter the IP address of the ENBT in one of the entries.

Click to expand...

This is the thing I forgot! I knew it would be something simple... Thank you!

I think I thought the Station Mapping window was for Modbus addresses or something... and I could have sworn that leaving it blank would still allow the module to browse and find my processor, but I guess not.

Unfortunately, my Logix is out of its grace period now, so I have to wait for the license procurement to go through before I can test that I can connect to it properly... but I'm pretty sure this was it!

The very old A-B "Data Highway" and DH+ networks called their nodes "stations", and the software that had built-in DH+ drivers always listed PLCs by their Station Number. When DOS and later Windows based multi-client comms drivers like Interchange and WinLinx and RSLinx came along, they had an API that allowed clients to address PLCs by Station Number.

So that's why there's a Station Number / IP Address table in the classic Ethernet Devices driver in RSLinx Classic.

That legacy driver always requires you to explicitly enter the hostname or IP address of a controller or comms module.

The more modern "EtherNet/IP" driver uses a broadcast packet to send a "List Identity" command that all EtherNet/IP compliant devices recognize and will respond to. That's why it is able to auto-magically browse all the devices that are on the subnet with the Ethernet network adapter you select to be associated with that driver.

Yes, you do need a null modem, only AB thing that takes straight serial are the panelviews from my own experience.