Does anyone have any experience with gigabit Allen Bradley Ethernet cards and communication speeds? I am looking to boost communication speeds from a L84 ControlLogix Processor (v. 35) to the Ignition OPC UA server (v. 8.1). I have around 42,000 tags, and am looking to get faster update speeds / poll rates. Can Ignition talk at gigabit speeds as long as all of the hardware is capable? Are there configuration settings to achieve this? My mean response time can fluctuate anywhere from 20 ms when nothing is being used on the HMI (I.e. leased tag groups aren't being used) to 80 ms when a significant amount of tags are being polled at faster rates.
I cannot change the overhead time slice for the PLC because of the newer version/hardware. But my message 3 communications on the diagnostics page of the PLC can fluctuate anywhere from 65% to 99%.
Any help in speeding up communications would be a great help. TIA.
I am assuming that the main (possibly only) task is the continuous task. You should really switch to periodic tasks if possible (a.k.a downtime is available), that will free up time for the controller to do communication tasks.
How much first class communications do you have? Many Remote Racks / VFD's / or other I/O type devices connected via Ethernet I/P?
I will definitely take a look at the driver for future projects. However, since we are a couple weeks from FAT, it wouldn't be feasible to implement at this point in time. Do you have more information on why gigabit speeds won't help communication? I didn't expect that answer.
Hi @lrose
We do have a continuous task. However, for L8 AB controllers, they have a separate communications processer. Would changing to a periodic task help if the communications are on a completely separate processor? Thanks.
Because you can saturate the PLC's comms limit with a 10 Megabit or 100 Megabit link. Adding Gigabit support to Rockwell's products is future-proofing against the commercial switches that have ports that don't support the older speeds. (Yes, really. I have some SFP+ copper phys that are 1Gb+ only.)
Not sure I agree with this. My driver is intended to be drop-in compatible with OPC Item paths from the native IA Logix driver. Some performance gains are available just by swapping drivers. Additional performance gains are available with an L5X export/import procedure that affects no PLC logic. (This procedure is recommended for IA's driver, too, but won't help with AOIs.)
If you can't pass your FAT with the current performance, I would highly recommend installing the module and using its trial mode to quantify the low-hanging fruit.
Yes. The message processor must coordinate tag access with the logic processor, particularly when CPS instructions are involved (I/O buffering should be using these). A continuous task will add random latency to the message processor's tag access. (Well, more random than a periodic task that runs at a pace deliberately chosen to match the application requirements.)
