Data transfer speed

I know this is an "it depends" question, but I'm curious about your answers. We promised colleagues from another company that Ignition would respond to an S7-1500 PLC within 100ms per signal. On the way, the data also pass through the OPC server. So the communication looks like this: PLC -> OPC server -> Ignition -> OPC -> PLC. Is it even possible to achieve 100ms response? What is the average time? We still have the issue that in Ignition the script must be executed first so that we can respond, and the question of whether it slows us down...

Definitely possible and definitely a it depends question. Did you know you can check OPC device response time from the Gateway's Status Connections Devices web page? This screenshot shows the response mean time for the different scan classes available.

Network latency and number of OPC tags will be some of the many factors at play here.

These don't mesh well. The answer is "probably not easily, and not for many tags."