Red Lion DSP Slow Update issues

hd_coop · Mar 26, 2010

Hello,
First some background:
I've got (2) similar machines setup to log some production data every 1 second using a Data Station Plus. The first machine works good, exactly like I expect.
The second machine logs data to the compact flash every second, but the data logged is only updated approximately 5-12 seconds. One of the pieces of data being logged is a timer acculated value with a 1 second time base so I know for a fact that the data is changing in the PLC.
Both machines are connected to a managed Cisco switch and are connected to our corporate intranet. I can add some of the data tags from Machine 2 to the Data Station in Machine 1 and the data updates properly so I believe I can rule out any PLC/Switch/Network issues. The PLC is an Allen Bradley SLC 5/05 in both cases.

About a year ago I tried working with Red Lion to resolve this issue but eventually had to just give up & live with it since this data isn't critical to us and I had more important things to worry about.

Fast forward to today:
I connected a Fanuc robot controller (RJ3iC I believe) to the Data Station in Machine #2. I can pass data between my PLC & Robot BUT I am also seeing this LOOOOOONG communications delay here....for example I have the Data Station setup to pass N80:11 to R64 in the robot and to also read back R64 from the robot to N80:10 in the PLC. After I change the value in N80:11, it takes about 5 seconds for the register to change in the robot, and another 5 seconds to be read back into N80:10. This long of a delay isn't something I can just live with anymore. Anybody ran into this before? Any ideas to try?
Thanks for any help!
-Josh

bkottaras · Mar 26, 2010

hd_coop said:
Hello,
First some background:
I've got (2) similar machines setup to log some production data every 1 second using a Data Station Plus. The first machine works good, exactly like I expect.
The second machine logs data to the compact flash every second, but the data logged is only updated approximately 5-12 seconds. One of the pieces of data being logged is a timer acculated value with a 1 second time base so I know for a fact that the data is changing in the PLC.
Both machines are connected to a managed Cisco switch and are connected to our corporate intranet. I can add some of the data tags from Machine 2 to the Data Station in Machine 1 and the data updates properly so I believe I can rule out any PLC/Switch/Network issues. The PLC is an Allen Bradley SLC 5/05 in both cases.

About a year ago I tried working with Red Lion to resolve this issue but eventually had to just give up & live with it since this data isn't critical to us and I had more important things to worry about.

Fast forward to today:
I connected a Fanuc robot controller (RJ3iC I believe) to the Data Station in Machine #2. I can pass data between my PLC & Robot BUT I am also seeing this LOOOOOONG communications delay here....for example I have the Data Station setup to pass N80:11 to R64 in the robot and to also read back R64 from the robot to N80:10 in the PLC. After I change the value in N80:11, it takes about 5 seconds for the register to change in the robot, and another 5 seconds to be read back into N80:10. This long of a delay isn't something I can just live with anymore. Anybody ran into this before? Any ideas to try?
Thanks for any help!
-Josh

I'm sure the Red Lion boys will answer but I have had similar setups with 5/05 - Compactlogix and rj3ic (RIO and ethernet/IP).
No issues with data exchange.
Both cases we were reading/writting to the robot I/O as well as reading/writting to the Robot registers.
I haven't used a DSP but hope this helps in some way to get things started for you.

hd_coop · Mar 30, 2010

Update w/ ethernet layout

Figured I'd bump this thread and post a sketch of the ethernet layout to help clarify. (Picture isn't the best quality because of size limitations)
I reprogrammed the Data Stations today so that the Data Station in Machine #2 was passing data between my PLC & Robot in Machine #1, comms sped up significantly...from ~10 seconds down to ~2 seconds including the update rate of RSLogix 500.

Anybody have ideas?

MikeGranby · Mar 30, 2010

Bump so it gets flagged on my list...

robertkjonesjr · Mar 30, 2010

Can you sniff the traffic with Wireshark? That would isolate which side of the connection might be the issue. If the Redlion is making requests but they are not answered, then the issue is the network or the remote device. Conversely, if the Redlion waits that long of a delay to make the request, then the issue lies with the Redlion.

You could use a bridge to do it, or if the managed switch supports mirroring, then it is even easier to capture the network data.

When I see significant delays I usually find that a comms timeout is active - so I try and check to be sure for that device that all requests are reasonable and answered promptly. If I request data that is not available or whatever, that's when the timeouts bite.

DanYost · Mar 31, 2010

Could you send your DSP and PLC programs to dany at redlion.net? I am curious to see if there is anything in there that could be causing communication errors, which in turn would cause a slower update than normal.

Regards,
Dan

hd_coop · Mar 31, 2010

I can try Wireshark but I'm not really sure how to use it very well....I've only used it in the past at Red Lion's request.

Unfortunately, since these switches are on our corporate network they are "owned" by IT, I can't access any configuration on them at all....it is also probably worth mentioning that both of these switches are on the same VLAN.

I don't see how it could be a network or PLC issue but am open to suggestions on things to try. One Data Station works fine, the other has a huge delay in communications. The one which works goes through (2) extra ethernet switches, that shouldn't make things better. The PLC & Robot are always plugged in in the same place. The Panelview has no comm issues.

I suppose one thing I could try is switching the slow Red Lion to a different port on the same switch.

Thanks.

Red Lion DSP Slow Update issues

hd_coop

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bkottaras

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