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@jinan There is a component in the TESS Controllers library that will do something very similar to what you described. Type 1233, Thermostatic Control with Specified Run Time, will set a control signal off of a thermostat input that runs for a user-specified minimum time and includes a minimum reset period before it can be restarted. The only difference from what you described is that Type 1233 runs the equipment for a minimum continuous period, not a maximum period. You could modify the source code of the Type to make the user-specified minimum time a maximum time instead, or you could use the trip timer (Type 1504, also in the TESS Controllers library) to monitor the length of time the equipment has been on, and use an equation block to connect a lockout signal to Type 1233 when the run time reaches the desired threshold.
Writing controls in equation blocks is difficult for a couple of reasons. For one, controllers usually make decisions based on the prior state from one or more past timesteps. Those can be recalled from a Type like Type 661 (Delayed Inputs, also in the TESS Controllers library), but can't be stored or accumulated directly within the equation block. Controllers also sometimes oscillate between 'on' and 'off' states multiple times before the solution for a timestep reaches convergence. (Imagine a tank is too cold, so a controller signals a heater to heat the tank, but the heating rate is such that the tank then overheats on that timestep, which signals the controller to turn the heater off, and the cycle repeats). Most TRNSYS controllers have a 'Number of oscillations permitted' parameter that limits how many times a controller may do this before its state is 'stuck' for the timestep, which records the condition in the .lst file and allows the simulation to continue. Equation blocks do not have the capability to 'stick' a controller based on an iterative state, so an oscillating controller in an equation block will eventually lead to convergence problems in the simulation instead.
