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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>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. <o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>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.<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>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. <o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>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).<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Michaël Kummert<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Polytechnique Montréal<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> Giulio Tonellato via TRNSYS-users <trnsys-users@lists.onebuilding.org> <br><b>Sent:</b> February 25, 2023 14:40<br><b>To:</b> trnsys-users@lists.onebuilding.org<br><b>Cc:</b> Giulio Tonellato <g.tonellato@hotmail.com><br><b>Subject:</b> Re: [TRNSYS-users] PID controller problem - TRNSYS Message 315<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB>I am having the same exact issue.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>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. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>The PID controllers control radiators with a certain air set temperature in the rooms.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>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.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>Did you solve it in the end? Anyone knows about this?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Regards,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Giulio<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>The message was by <b>Mariam Elnour</b><br><i>Mon Aug 6 07:38:12 PDT 2018<o:p></o:p></i></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-GB>Dear TRNSYS users,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB> 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,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>"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"<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Is there a way to solve this issue?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Thank you.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>-------------- next part --------------<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>An HTML attachment was scrubbed...<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>URL: <</span><a href="http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20180806/322b110d/attachment.html"><span lang=EN-GB style='color:windowtext;text-decoration:none'>http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20180806/322b110d/attachment.html</span></a><span lang=EN-GB>></span><span lang=EN-GB style='font-size:10.0pt'><o:p></o:p></span></p></div><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p></div></body></html>