SLC 5/05 slow ethernet comms

[sfindley]

I have two SLC 500 5/05E processors on a subnet with a Delta motion controller. I am using OPC and Topserver for I/O comms and Wonderware for HMI interaction. When I am online with one of the PLCs using an Ethernet driver, the ladder icon barely moves and updates are excruciatingly slow. The HMI also takes a long time to update. A packet sniffer reveals that the other PLC is communicating with the TopServer twice as much as the one that is slow and the "fast" PLC seems to update pretty well.

I've seen posts about settings in RSLinx and none of them seem applicable...not using a PIC.

Curious if anybody else has seen really slow update times and what they did to alleviate them. Our program is rather large with a few BTW/BTRs in it. Can't find anything that is a smoking gun to slow things down. Scan time is nearly identical on both PLCs also.

 

[hd_coop]

Under Processor Status, Chan 1 tab...does either PLC have the "Comms Servicing Sel S:2/15" set to 1?

 

[sfindley]

Yes, both have it selected to 1.

 

[jac]

I have found a SLC505 is slow dealing with a large communication load even doing a upload for that matter. You can try one or two SVC (Service Communications) instructions stuck in between you JSR's to update the comm's more often. This will of course be paid with some scantime...


SVC

Channel 0 = serial port
Channel 1 = Enet

I hope all HMI tags are in contiguous files for efficient comm's.
SVC [Service Communications]

 

[sfindley]

I set the S:2/15 bit to 0 and saw a marked improvement in update with minimal impact on scan times. Unfortunately, our HMI tags are not as contiguous as I'd like them to be since they've been made over several years by many technicians as we learn our way in automation. That is the next step...thanks for your prompt (and helpful) replies.