Initialising outputs during PLC boot

There are applications for which the default value (zero) assigned initially or under particular operating conditions to the Output variables, when they are not digital or analogue outputs of HW/IO devices but the functional parameters of an intelligent device connected with a fieldbus (e.g.: CANOpen), is not a correct value. For these cases a dedicated output initialisation management has been added.PLC Gefran PLC start sequence:Start acquisition and processing of the I/O configuration and of the fieldbus. Await completion of all the phases, particularly the processing of the configuration of the I/O of the GDNet devices which is developed parallel. The communication of the fieldbus and the I/O exchange is not activated.Start of the applicative program: if present, the BOOT task is run followed by the INIT.Start of I/O management: after running the INIT task or (in the absence of the latter), the communication of the fieldbus and I/O exchange are activatedStart of the applicative program: running of all the other tasks of the applicative programAccording to this diagram, the INIT task is run when fieldbus and I/O exchange communication are not yet underway. It is therefore possible to add instructions to this task that assign appropriate and valid values to the Output variables right from the first I/O exchange run.If using the INIT task, it is necessary to consider that its running is not related to the Power-on phase only, but also in the case of Full download or PLC Start command from the configuration environment.It is possible for the running of the INIT task to initialise all the variables (output and others) to exceed the default conditions for operation of the watchdog, triggering it with the consequence stoppage of the PLC program.To be able to manage this specific condition, it is possible to configure the run timeout envisaged for the INIT and BOOT tasks within the Options configuration of GF_Project VX, section Plc1131.