SLC5/05 Connection Question/Problem

[Gil47]

The way you are describing the comms ports on this PLC,
it most likely is still on the default ethernet address for SLC 5/05,
which at the moment I can't remember I think
its something like 192.XXX.XXX.XXX
but hopefully others can fill in the blank xxx

 

[DwSoFt]

Patch. Crossover. Same thing. That was what I was referring to. 192.168.0.xxx maybe

 

[Ken Roach]

Allen-Bradley controllers do not have a default IP address.

Allen-Bradley controllers never use Automatic Private IP Addressing (APIPA).

While 192.168.0.x and 192.168.1.x are very common private Class C subnets, they are not defaults or preferred by the controllers.

Some A-B I/O devices like POINT I/O and FLEX I/O have a mode where they can be set for 192.168.1.x by using pinwheel switches. The SLC-5/05 does not, nor do any controllers of which I am aware.

By default, they are configured to use BOOTP and DHCP protocols to get an IP address from a BOOTP/DHCP Server. This can be any valid IP address that the server is configured to assign. A good lightweight BOOTP/DHCP utility is included with and installed with RSLinx Classic.

 

[Aabeck]

While 192.168.0.x and 192.168.1.x are very common private Class C subnets, they are not defaults or preferred by the controllers..

Ken,

Thanks, I was thinking of trying the 256 possible 192.168.0.x addresses, but I would have been wasting my time.

 

[MarkNightingale]

I agree with Ken.

I have my laptop set at a completely different address 25.6.32.87, and as you can see from the picture I have been able to capture the address of the PLC 10.64.7.2 using Wireshark.

Cheers

Mark

 

[Aabeck]

I connected Wireshark & ended up with a list almost 4000 lines long before the MAC address of the SLC5/05 showed up, (powered it down & got the # off the side) but as the picture attached shows, no IP address, only a boot request. I even tried the addresses shown of 0.0.0.0 & 255.255.255.255, but not good #'s for RSLinx. Still couldn't connect to it.

 

[Ken Roach]

Thanks for posting that !

What you saw in Wireshark is the SLC-5/05 sending out a BOOTP request. There needs to be a BOOTP Server on the network that's able to give it an IP address in response to that request.

Start -> Programs -> Rockwell Software -> BOOTP/DHCP Server -> BOOTP/DHCP Server.

Configure the Tools -> Network Settings menu item so that the utility knows what Default Gateway and Subnet Mask to assign, then when you see the request from the SLC-5/05 you can make an entry in the IP assignment table for it. The next request will be responded to by the server, and the controller will have an IP address you can use.

The most common settings are a Subnet Mask of 255.255.255.0, and a Default Gateway of 192.168.1.1. Those are the only two required settings. The Default Gateway has to be on the same IP subnet as your computer; do an "IPCONFIG /ALL" to verify the IP address your computer is using.

This address will only persist until the next power cycle, or if you disable the BOOTP/DCHP option using RSLogix 500.

 

[Aabeck]

Ken,

Thanks, hopefully I can get back to this shop tomorrow to try that.

 

[Aabeck]

Got back to the customer this morning, fired up Wireshark - connected to the switch in the panel. Ran over 45 minutes with 1000's of entries for my laptop & the computer running the HMI. Lots of entries for RSLinx Self Tests running on the 2 computers. Finally got a Rockwell MAC address show (see top line of picture) but the 2 addresses (WhoHas & Tell) were not good for RSLinx. Wireshark is still running trying to find more entries.

Still cannot connect (through DF1 or UIC) to RS232 port also.

Any ideas?

 

[Luke_Mages]

Got back to the customer this morning, fired up Wireshark - connected to the switch in the panel. Ran over 45 minutes with 1000's of entries for my laptop & the computer running the HMI. Lots of entries for RSLinx Self Tests running on the 2 computers. Finally got a Rockwell MAC address show (see top line of picture) but the 2 addresses (WhoHas & Tell) were not good for RSLinx. Wireshark is still running trying to find more entries.

Still cannot connect (through DF1 or UIC) to RS232 port also.

Any ideas?

did you try the bootp as ken suggested? you don't need wireshark anymore, wireshark verified that the slc was sending the bootp request.

 

[Aabeck]

Luke:

Since the PLC is communicating with a PC based HMI I figure it has to already received BOOTP from that PC. When I fired up BOOTP on my computer it wanted me to assign an IP address - which if I changed would screw up the HMI comm's I would think. And, I can't access the IP address that the HMI is talking to from the HMI PC.

With Wireshark still running the only Rockwell MAC address is the ARP Request, same one in the picture above with the same 2 WhoHas & Tell addresses that don't seem to be right.

 

[krakenfan69]

If the PLC is connected to an HMI can you not open that program and see what communication protocol it is using and then disconnect the HMI and connect to t he PLC to do an upload , set an IP address and then connect via ethernet and reconnect the HMI?

Kraken Fan #69

 

[Aabeck]

The HMI is run on Proficy iFix, and the normal windows functions are not accessable with iFix running, like can be done on other HMI programs - I would have to shut the line off, something the customer doesn't want today.

Also, Wireshark is not showing any BOOTP request for an IP address, just an ARP message, so the PLC must have already got it's IP address.

Left Wireshark running while I went to lunch & it still only came up with the same ARP as in my picture above.

 

[JordanCClark]

According to the ARP packet and the MAC address it came from, 172.16.0.211 is the IP address of the PLC.

It goes something like this: IP address 172.16.0.211 has something to tell 172.16.0.1, but it doesn't know what MAC address to send it to. So it sends out an ARP (Address Resolution Protocol) packet to try and figure it out.

Further info:
If memory serves, the '204' error you see in RSLinx is a straight-forward timeout. If I were to take a stab at this, I'd say your own IP address doesn't match up to the subenet. (172.16.0.x)

 

[JordanCClark]

I'm going to retract some of this. The logic is still sound, but what I'm noticing is that the MAC addresses aren't the same between your two posts. So where is the second MAC coming from?