This test function returns the condition of a selected operand (inputs, outputs, flags, dataword, counters or timers) at the end of program execution. This information is obtainedfrom the corresponding area of the selected operands. During the controlling of variablesrespectively in operating mode STOP the input area is directly read. Otherwise only theprocess image of the selected operands is displayed.n Control of outputs– Serves to check the wiring and proper operation of output modules.– If the CPU is in RUN mode, so only outputs can be controlled, which are not con-trolled by the user program. Otherwise values would be instantly overwritten.– If the CPU is in STOP - even without user program, so you need to disable thecommand output lock BASP ( ‘Enable PO’ ). Then you can control the outputsarbitrarilyn Controlling variables– The following variables may be modified: I, Q, M, T, C and D.– The process image of binary and digital operands is modified independently of theoperating mode of the CPU.– When the operating mode is RUN the program is executed with the modifiedprocess variable. When the program continues they may, however, be modifiedagain without notification.n Forcing variables– You can pre-set individual variables of a user program with fixed values so thatthey can not be changed or overwritten by the user program of the CPU.– By pre-setting of variables with fixed values, you can set certain situations foryour user program and thus test the programmed functions.CAUTION!Please consider that controlling of output values represents a potentiallydangerous condition.Even after a power cycle forced variables remain forced with its value,until the force function is disabled.These functions should only be used for test purposes respectively fortroubleshooting. More information about the usage of these functionsmay be found in the manual of your configuration tool.4.20 Diagnostic entriesÄ Appendix A ‘System specific event IDs’ page 325n You may read the diagnostics buffer of the CPU via the Siemens SIMATIC Manager.Besides of the standard entries in the diagnostics buffer, the VIPA CPUs supportsome additional specific entries as Event-IDs.n To monitor the diagnostics entries you choose in the Siemens SIMATIC manager‘PLC è Module information’. Via the register "Diagnostics Buffer" you reach the diag-nostics window.n The current content of the diagnostic buffer is stored at the memory card by means ofthe CMD DIAGBUF.Ä Chap. 4.18 ‘CMD - auto commands’ page 114n The diagnostic is independent from the operating mode of the CPU. You may store amax. of 100 diagnostic entries in the CPU.‘PLCè Monitor/ModifyVariables’Accessing diagnostic dataVIPA System SLIO Deployment CPU 013-CCF0R00Diagnostic entriesHB300 | CPU | 013-CCF0R00 | en | 19-30 117
