MLogix 1100 - PLC 5/40E EthernetI/P messaging

Hello all,

I am trying to poll data into a MicroLogix 1100 from a PLC 5/40E over Ethernet I/P. My MicroLogix program contains a single message instruction triggered periodically by a self-resetting timer. (I have used message instructions a lot so you can be assured I have the messaging logic setup right).

Attached pictures show the message setup screen. When enabled, the message errors out saying ... "The connection was timed out by the network". Error code "d6".


The ethernet network is simple with just a switch between the two PLCs. I can plug a laptop into the switch and go online with both PLCs. They are in the same subnet with IPs 53.235.11.80 and 53.235.11.81. I have no clue why my message errors out and I do not understand the error message.

One important thing is that previously the PLC5 was on the plant network through a router. It has a gateway address in it 563.235.8.1 and the subnet mask is 255.255.252.0 (I tried using the same subnet mask on the MLogix). I dont know if these are the cause of the problem and I cant put it in program mode to change these settings without authorization.

Rockwell TechConnect has no clue about the solution. They suggested a firmware upgrade. The MLogix 1100 has FRN 5.0 on it and the latest is FRN 7.0. I am going to try this but dont know if thats my problem.

Seems like I had a problem with Gateways before, but with an 1100 and a PanelView. May need to remove the Gateway from the PLC5, or add it to the 1100 since you can't access the PLC5. Then maybe set your laptop as the Gateway address. I don't know about that part. I think I would try to get permission to get rid of it in the PLC5 . Also you say you've used Message instructions a lot, but have you used them a lot with the 1100? There are some new things in there (MG Data Files, etc.).

I'm FAR from a guru... but, isn't the subnet mask value 252 (11111100) preventing a match with the 11 (00001011) in the IP address, thus causing the PLC-5 to try to go thru the gateway.

Don't forget about the difference between EtherNet/IP messaging and CSPv4 messaging.

The original PLC-5E controllers used a proprietary A-B protocol called CSPv4. ControlLogix, 1761-NET-ENI, and MicroLogix 1100 controllers use only the newer EtherNet/IP messaging protocol.

All PLC-5E controllers can be upgraded to support both CSPv4 and EtherNet/IP.

The firmware versions that the PLC-5E needs are on the Rockwell knowledgebase (and RA support knows very well that this is the case).

dougrb said:

I'm FAR from a guru... but, isn't the subnet mask value 252 (11111100) preventing a match with the 11 (00001011) in the IP address, thus causing the PLC-5 to try to go thru the gateway.

Click to expand...

No, the third octet is 11 for both addresses, so it is on the same network. The way subnet masking works is a little different than you understand. The subnet mask indicates which bits are used for the network address and which are used for the host. As long as all the network bits are the same, the other host is on the same network. Thus, with a subnet mask of 252, only the first 6 bits are used for the network address, the last two are used for the host. With his subnet mask, .8 (00001000), .9 (00001001), .10 (00001010), and .11 (00001011) are all reachable on the local network because the first 6 digits are an exact match. 12 (00001100) would not be reachable because the first six digits are different than our localhost's address.

Hope that clears it up a bit. If you have any questions, just ask.

Brian

Try using messages from the PLC5 only, if you can. There's a lot less overhead in that processor. There doesn't need to be message instructions on both ends (of course!). Differences would be alarm reporting or any condition that requires immediate notification. Still, you can poll every 15 seconds and still be ahead using the PLC5.

Tom,

I have not programmed PLC5 before so I dont know if I can add a message instruction to it online in Run mode. I dont want to spend another trip on site to find that out. Do u know if this can be done?

(If someone finds out that I changed the program in the PLC5, I might get into some trouble but I guess a couple rungs wont hurt anybody)

A firmware upgrade on the PLC5 is totally out of the question. Actually I cannot even put it in program mode since if the process doesnt work right when put back in Run mode, it would be upto me to troubleshoot everything.

Brian123 said:

The way subnet masking works is a little different than you understand.Brian

Click to expand...

Probably! Thanks for the clarification.

puravdagli,

You can add a message instruction online as long as there is an available MG data type for the control word.