Latency when using Ignition with PLC

Ignition
1

Hi,

We are working on an industrial machine where Ignition is used between the HMI and a PLC.

We are experiencing noticeable latency when triggering commands such as start/stop from the HMI, which affects the consistency of the process.

Is it considered good practice to use Ignition in such control paths, or should time-critical commands be handled directly by the PLC or via direct I/O instead?

Thanks in advance for your insights.

2

What type of PLC? Chances are you are reading too much data from the PLC which is bogging down the comms.

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3

If you're talking about a local HMI to the equipment, I always recommend keeping it independent of any other HMI or SCADA system to go directly to the PLC. This way you always have a local control and monitoring HMI that doesn't rely on other systems to function.

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4

This, almost certainly. Perhaps with unrealistic expectations for update rates for your PLC's comms capacity.

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5

Are you talking about it causes issues with other places? Like are you using system.tag.writeBlocking instead of system.tag.writeAsync for all your commands?

Or are you talking you click a button and nothing happens for a few seconds?

6

Need to know:

  • Plc make and model
  • Number of tags you’re reading
  • For AB PLCs, what types of tags (UDTs, AOI parameters or locals, standard)
  • What is the overload on the plc seen from the gateway web portal for the device? (show us a screenshot)
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