# Latency when using Ignition with PLC **URL:** \ **Category:** Ignition\ **Tags:** ignition80\ **Created:** [April 13, 2026, 11:22am UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039 "2026-04-13T11:22:57Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![onderhoud](https://avatars.discourse-cdn.com/v4/letter/o/f475e1/32.png) [@onderhoud](https://forum.inductiveautomation.com/u/onderhoud)\ **Post date:** [April 13, 2026, 11:22am UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/1 "2026-04-13T11:22:57Z")
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. ---
**Author:** ![bschroeder](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bschroeder/32/13260_2.png) [@bschroeder](https://forum.inductiveautomation.com/u/bschroeder)\ **Post date:** [April 13, 2026, 11:31am UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/2 "2026-04-13T11:31:09Z")
What type of PLC? Chances are you are reading too much data from the PLC which is bogging down the comms. ---
**Author:** ![michael.flagler](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/michael.flagler/32/26272_2.png) [@michael.flagler](https://forum.inductiveautomation.com/u/michael.flagler)\ **Post date:** [April 13, 2026, 1:16pm UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/3 "2026-04-13T13:16:38Z")
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. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [April 13, 2026, 1:41pm UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/4 "2026-04-13T13:41:55Z")
> [@bschroeder](#): > > bogging down the comms This, almost certainly. Perhaps with unrealistic expectations for update rates for your PLC's comms capacity. ---
**Author:** ![Nol](https://avatars.discourse-cdn.com/v4/letter/n/8e8cbc/32.png) [@Nol](https://forum.inductiveautomation.com/u/Nol)\ **Post date:** [April 13, 2026, 2:54pm UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/5 "2026-04-13T14:54:51Z")
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? ---
**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\ **Post date:** [April 13, 2026, 3:06pm UTC](https://forum.inductiveautomation.com/t/latency-when-using-ignition-with-plc/115039/6 "2026-04-13T15:06:28Z")
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)