Emulation Subscribe to Changes / Poll for External Changes

[steven_chen1]

[ FlexSim 19.1.1 ]

Hello,

I tested the tutorial 1 with Omron PLC through Modbus TCP. I got serious latency time on simulation.

Because I want more accuracy on controlling the motor, so I set the change interval to 0.1s in case it's too late to stop the motor. When "Poll for External Changes" is checked, it created poll event every 0.1s in order to update the controls status. I tried a modified model that use 4 polling controls and it's hard to run and freeze.

Since I knew that PLC's output only changed if input changed, is it possible to make Flexsim do polling while input changed?

[benjamin_w2]

Hi @steven.chen, can you upload a copy of your model? It will help us to debug it. Make sure to tag @Benjamin W2.

[steven_chen1]

@Benjamin W2

Sorry for late reply. There are 14 controls polling data from PLC in the model. The model is freeze/lag for about 200ms on data polling every 0.5s.

test-emulation-poll-lag.fsm

[joshua_s]

@steven.chen

Have you still noticed a lag like this still when working with PLCs? What was the logic on the PLC? How were you measuring the lag?

[steven_chen1]

Hi @Joshua S,

It killed frame rate a lot when connect with PLC. I learned that setting runspeed to 1.0 is necessary or FlexSim will be freeze totally. About the logic of PLC, I didn't do anything toward these copied registers (values won't change).

[cole_s3 · Accepted solution]

Closing outdated question