1756-l61 1756-enet/b 1734-aentr

I did a small system for a customer that has three nodes of EIP. This is one station on a larger machine and customer wanted control to be merged into their equipment. Therefore I developed the program and debugged the machine with a little L23E PLC to control things at my shop. The plan was then to port the code over to the customer's PLC when finished. This is exactly what we did with a virtually identical machine last year on their floor with no issue.

Yesterday after adding the code to their L61 processor, everything transferred fine and all the communications were good except for the 1734-AENTR module. The all familiar "IO not responding" light blinks and the AENTR shows the little yellow triangle in the IO tree. It keeps going between connecting and connection timeout. Everything is setup exactly as I had it on my CPU. I checked for a duplicate IP for that node and there were none. I tried it with and without Unicast. The 1734-AENTR modules itself shows no signs of problems. All the status and communication lights are green. It pings fine (although there is some latency). The system is as follows.

1756-L61
1756-ENET/B
1734-AENTR

Both I and the customer are in Ver20 RSLogix.

I am perplexed as to what the problem is.

What is the firmware revision of the 1734-AENT ?

I found that my v.1 adapter did not work with V 20 of RSLogix 5000, and RA suggested only adapter firmware v. 3 would. The connection cycling behavior was similar.

Bonus: the AENT is not field upgradeable from v1 to v3.

Ken Roach said:

What is the firmware revision of the 1734-AENT ?

I found that my v.1 adapter did not work with V 20 of RSLogix 5000, and RA suggested only adapter firmware v. 3 would. The connection cycling behavior was similar.

Bonus: the AENT is not field upgradeable from v1 to v3.

Click to expand...

Hi Ken

It is a 1734-AENTR series A rev 3.1

Well, then, that's not it.

An EtherNet/IP network really shouldn't show any significant latency. How many milliseconds are we talking about ?

I wonder if there is something physically wrong with the client network that is causing timeouts. The module diagnostic webpages are a good place to start investigating.

I had the same situation but it was with 1794-AENTR and a 1756-EN2TR had to upgrade the EN2TR to v4.0 or higher...

Things got a little more interesting, but definitely not better. Spent a good four hours or so yesterday evening trying to resolve this to no avail. What I found was:

The time latency I was experiencing was just on my PC due to the manner that I was connecting to the company network. When I hooked up direct with a static IP the pings were extremely fast (1 to 2 ms).

Customer actually has a 1756-ENBT/A and not the ENET that was showing in the configuration tree. Remarkably, the rack had been functioning this way for quite some time with the wrong configuration. There were no faults or any other indicators in RSLogix5000 that showed an issue. We fixed the configuration thinking for certain that this must be the cause of the problem, but it did not.

Tried both ports on the AENTR. Tried auto negotiation and fixed baud. Tried deleting the configuration from the tree and re-entering from scratch. Tried with and without Unicast.

Noticed the the "Alignment Errors" bit flashes on periodically and that the AENTR is showing MAC receive errors. Attached is the screen shot of the port diag. Also curious about the "unknown Protocol" packet counter.

It never ceases to amaze me that the most difficulty I have with AB products is getting them to work with other AB products. After also wasting about four hours trying to get FT7.0 to install correctly as well it pretty much blew the whole day.

Ok, now that I know it is an 1756-ENBT I found the following knowledge base article.

62938 - Error 16#0203 on 1734/1738-AENTR Modules

It specifies FW 4.5 or greater and I know when we looked at it yesterday it was 3 something. With any luck, once the FW is updated the problem will go away.