the likely cause of the warning is that you are using the PID controller (Type 23) in “real time” mode (Mode 0) and that you built your project by adding some of the controlled components (components which use the PID output) after you added the PID to the project. In Mode 0, the controller calculates its output at each iteration within a given time step, but only applies the result (i.e. updates its output) after convergence has been reached, so that the calculated control signal is applied at the next time step, not at the current time step. When you use that mode, if the PID is placed before the component it controls in the “calling order” of TRNSYS, the controlled component will receive a non-updated output (which is exactly what you want). TRNSYS warns you about it, and the message is clear that it’s not necessarily an error but it’s unusual – and it could be an error in some specific cases. In this case the behaviour is not an error, so you can safely ignore the warning, but if you want to suppress it, the easy way is to make sure that the PID controllers are located after all components they control in the input file. You can change that in “Component Order” in the Studio (Gear icon or Assembly > Settings, then Component Order). Just drag all PIDs below the components they control. By default, components are placed in that list in the order you add them to the project, so this may explain that some early versions of your project were not causing any warning (because the PIDs were added after the components using them). Michaël Kummert Polytechnique Montréal From: Giulio Tonellato via TRNSYS-users <trnsys-users@lists.onebuilding.org> I am having the same exact issue. It came up super randomly when activating my air handling unit that is heating up the air. I say randomly because it never appeared before even with the AHU on. The PID controllers control radiators with a certain air set temperature in the rooms. Only thing I changed lately was the pipes’ geometry before and after radiators, but now changing it back does not seem to solve the problem. Did you solve it in the end? Anyone knows about this? Regards, Giulio The message was by Mariam Elnour Dear TRNSYS users, I am having a problem with PID controllers performance . I tried modifying the components order however I still get the same warnings on all PID controllers units used in the project. The TRNSYS Message 315 is as follows, "The TRNSYS processor has reported a potential problem with the connections in your input file. In version 16, there is a very specific calling order after convergence has been reached at each timestep. One of your connections flows against this calling order - for example you may have the output of an integrator connected as an input to a standard component (one that is being called iteratively at each timestep). While this is not technically an ERROR - it may cause incorrect values to be passed to the component. For example, the input to an iterating component from an integrator will be from the previously converged timestep and not the current timestep. Refer to the TRNSYS Manual - Volume 1 - for more information on the calling order for TRNSYS components" Is there a way to solve this issue? Thank you. -------------- next part -------------- An HTML attachment was scrubbed... |