HIMax Safety Manual - Tuv-fs.com

10 User program HIMax10.2.5 Downloading and Starting the User Program10.2.6 ReloadA PES in the HIMax system cannot be downloaded until it is set to the STOP state.Currently, only one user program can be loaded into a given PES. The system monitorsthat the user program is loaded completely. Afterwards, the user program can be started,i.e. the routine begins to be processed in cycles.If the user program was modified, the changes can be transferred to the PES duringoperation. After being tested by the operating system, the modified user program isactivated and it assumes the control task.iNote that the reload does not take the current state into account if changes are performedto user programs containing a finite state machine. This can lead to an unpredictableprogram behavior after the reload process. A program contains a finite state machine if it iscomposed of sequential function chart elements such as steps, or function blocks withstorage capacity, e.g., RS Flipflops.In such a case, the execution of a reload must be planned thoroughly!Prior to performing a reload, the operating system checks if the required additional taskswould increase the cycle time of the current user program to such an extent that the definedwatchdog time is exceeded. In this case, the reload process is aborted with an errormessage and the controller continues operation with the previous user program.iReload can be abortedA successful reload is ensured by planning a sufficient reserve for the reload whendetermining the watchdog time or temporarily increasing the controller watchdog time by areserve of at least 30% and by at least 4*X ms.Any temporary increases in the watchdog time must be coordinated with the responsibletest authority.The reload can only be performed if the "Reload permitted“ system parameter is set to ONand the "Reload deactivation“ system variable is set to OFF.iThe user is responsible for ensuring that the watchdog time includes a sufficient reservetime. This should allow the user to manage the following situations:• Variations in the user program's cycle time• Sudden, strong overloads in a cycle, e.g., due to communication• Expiration of time limits during communication10.2.7 Online Test / Single Step ModeOnline test fields (OLT fields) can be used in the user program logic to display variableswhile the controller is operating.For more information on how to use OLT fields, enter "OLT field" in the SILworX onlinehelp.To diagnose faults during the online test, the user program can be run in single steps, i.e.,cycle for cycle. Each cycle is triggered by a command from the PADT.This function can only be used if the Freeze allowed system parameter is set to ON in thecorresponding user program.Page 56 of 70HI 801 003 D Rev.2.0