Since adding 2 PanelViews to SLC5/04 DH+ network, the network bogs down. The "update frequency" parameter does not seem to do anything, but switching the screen to one that has few or no embedded variables helps a lot. I could have done a better job on grouping my data together and that will be my next effort, but will require a lot of code to be re-written. Any other thoughts? I never had these problems with PanelMates and DH+, I would have thought the AB product would have been better, not worse.

 

HMIs (human-machine interfaces) are by nature pretty "chatty" devices. I always try to keep them on a separate network such as RS232 or something totally local to the PLC. If there is any data to be imported from outside the PLC, then I use the PLC network to move it around, via DH+ or EtherNet or whatever, and then let the local network move it from the PLC to the HMI. This way the HMI is not on the main network and does not add extra overhead.

Gerald Beaudoin

 

I agree - plus newer SLC5/04 firmware can act as a "bridge" or "pass-thru" (do a search at www.ab.com in their knowledge base). You could move the PanelView to the DF1 RS-232 port of a SLC5/04, enable the bridging, and then adjust the baud rate up/down to balance the impact in PanelView update time verse DH+ network impact. The SLC5/04 then uses the DF1 DST byte to route to other DH+ nodes on PanelViews behalf. This will impact the local SLC5/04 a bit, but probably much less than your currect system-wide impact on the DH+.

- LynnL, www.digi.com

 

Suggest you check firmware revisions on the 504, last one we installed did not support pass-thru, AB said it would be corrected in next firmware revison, I think they said rev. 7

Best, ray pike

 

Take a hard look at how alarming is being handled in your PV app, PV alarms will seriously chew up your comm bandwidth, utilize the the alarm word and offsets per the PV manual it will save you tons of bandwidth.

 

Panelviews think they are the only device on the network. We tested 4 SLCs with 1 and 2 panelviews with network bandwidth (albeit DH485 but the principle exists) and the performance dropped huge with 1 PV connected, and was distant with both. They just pound the network!!

Cheers from: Jeremy Pollard, CET The Crazy Canuckian!
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