SLC 5/05 Ethernet comms *very* slow

[kolyur]

Can anyone suggest why the Ethernet port on my SLC 5/05 is sometimes very very slow when communicating with RSLogix?

I have the SLC on a network with a Panelview 1000 and Red Lion G3 through an N-Tron switch. Comms between the three devices are very fast and reliable, however when I try to download or upload a program to the SLC, it can take 2-3 minutes to complete. (If I download to the serial port on the PLC it takes about 15 seconds for the same program.)

The problem is very sporadic--sometimes Ethernet uploads/downloads will be as fast as the serial port, other times not. And the problem still exists if I connect directly to the SLC with a crossover cable, so I don't believe it has anything to do with the other hardware. I have tried changing bits S:2/15 and S:33/7 as suggested in other posts, with no effect.

 

[John Soltesz]

I had problems with on-line program changes where it would fail to accept the change and drop offline. Our local rep had a fix that was just a change in RSLinx that seemed to help. I don't recall what it was and I am not in my office for a few days. He did say there was a technical bulletin out about some of these ethernet issues. I tried this late last year and haven't had any problems.

 

[kolyur]

Thanks for the response. I think you are referring to the CIP options in RSLinx and reducing the number of fast/slow messaging connections. I believe I already changed this setting some time ago after I found that tech bulletin.

 

[ArikBY]

505 Et

I had also the same problem.
Like John Soltesz wrote it is problem of RS-Linx setting.
I search the web and I found AB publication about that and it OK since.
I did not save it.I think it will be easy to found.

 

[Mickey]

KnowledgeBase ID 32963 (or see PDF works for SLC5/05 also)

 

[ArikBY]

That exactly what I used.
If I remember well I had problem of On-Line edis too.

 

[kolyur]

Update

OK I still have not solved this problem but I discovered something puzzling that I thought I'd throw out there in case anyone has experienced the same problem.

I actually have three other PLCs on this network besides the 5/05--two are ML1200s with NET-ENIs and the other is a ML1100. I didn't mention them before because they are not communicating with the SLC or Panelview; I just put them on the network for ease of programming. I don't have any speed problems when uploading or downloading to these other PLCs; they are very fast.

The puzzling thing is that if I am online with any of these three other PLCs in another instance of RSLogix, communication with the SLC immediately speeds up. As long as I am online with another PLC at the same time, I can upload or download my program to the SLC in about 15 seconds (vs. 2-3 minutes otherwise). The ladder icon is spinning fast, online updates are quick, everything is great. But as soon as I shut down the other RSLogix, SLC comms slow down to a crawl again.

Can anyone explain this?

 

[automaITion]

- Try another computer (maybe the problem is with your computer).
- Do the other PCs have the same IP subnet as the SLC ? if they're on different subnet then maybe your network addressing is the issue.
- Ping the PLCs and SLCs continuously (use -t). What's the reply time ?Then go online with the PLC, what's the reply time now.
- by the way, ethernet communication should be way faster than serial so if you got even the same speed then there's already a problem with the ethernet.

 

[mgvol]

If your 5/05 is older than a Series C, it is only capable of 10Mbps/Half-Duplex communication. If this is what you have, your ethernet switch needs to be a managed switch, so you can force the port the 5/05 is connected to for 10 Mbps/Half-Duplex. Those older 5/05's and ethernet PLC-5's don't play nice with autonegotiate switches. What you are describing is one of the symptoms of this.

 

[DaveW]

Also try clearing Comms Servicing Selection S:2/15 and Msg Servicing Selection S:33/7 bits. They allow more time for ch1 communication servicing but be careful as your scan time may increase.

 

[kolyur]

Thanks for everyone's suggestions.

All the devices are on the same subnet, but I will try pinging the PLCs to check the response time.

I am pretty sure my SLC is Series C but I will double-check. I am using two unmanaged N-Tron switches to connect everything.

I unlatched the two bits mentioned by DaveW but didn't see any difference in my communication speed or scan time (about 8ms now).

I am also going to try using a different computer to see if it's an issue with my laptop.

 

[nrwicks]

Did you resolve your issue?

 

[kolyur]

Nope.

But the machine is running fine so I haven't had a need to connect my laptop in the past 3 years.

I suspect it might be a problem with my laptop, but I never took the time to try a different one.

EDIT:
On later projects I discovered that it helps to put one or more SVC instructions at various places in your program, to service the Ethernet comms more frequently. This does slow down the scan time, though.

 

[Bit_Bucket_07]

Thanks for everyone's suggestions.

All the devices are on the same subnet, but I will try pinging the PLCs to check the response time.

I am pretty sure my SLC is Series C but I will double-check. I am using two unmanaged N-Tron switches to connect everything.

I unlatched the two bits mentioned by DaveW but didn't see any difference in my communication speed or scan time (about 8ms now).

I am also going to try using a different computer to see if it's an issue with my laptop.

Clear Bit S:2/15 and Set Bit S:33/7. Bit S:33/7 is ignored if Bit S:2/15 is Set.