HIMax Safety Manual - Tuv-fs.com

7 Input Modules HIMaxNOTICESystem malfunction possible!The slots reserved for processor and system bus modules must not be used forinput modules!!7.5 Safety-Related Digital InputsThe digital input module reads its digital inputs one time per module cycle and stores thevalue internally. The module cyclically checks that the inputs are safely functioning.Input signals that exist for a time shorter than the time between two samplings, i.e. shorterthan a cycle time of the input module, are not be detected.7.5.1 Use of Digital InputPerform the following steps to use the value of a digital input in the user program1. Define a global variable of type BOOL.2. When defining the global variable, enter the initial value as safe value.3. Assign the global variable to the channel value of the input.The global variable provides the safe value to the user program.For digital input modules for proximity switch internally operating in analog mode, the rawvalue can also be used and the safe value can be calculated in the user program. Refer toChapter 7.7.1 for more information.To get additional options for diagnosing the external wiring and programming fault reactionsin the user program, assign global variable to Channel OK and to further diagnosticstatuses. For more information on the individual diagnostic statuses such as line shortcircuitsand line breaks, refer to the manual of the corresponding module.7.5.2 Test RoutinesThe online test routines check whether the input channels are able to pass both signallevels (0 and 1 signals), regardless of the signals actually present on the input. Thisfunction test is performed each time the input signals are read.7.5.3 Reaction in the Event of a FaultIf the test routines detect a fault of a digital input, the module sets the channel value in away that the global variable assigned to the channel assumes the following values:• For the most faults, the global variable assumes its configured initial value..• For certain types of faults the module is able to put the channel into the safe state, butthe module cannot issue a diagnosis entry.For these faults, the global variable adopts the value 0.The module sets the status Channel OK to FALSE.If the test routines detect a module or submodule fault, the module sets the Module OK orSubmodule OK status to FALSE. Additionally, the module or submodule sets Channel OKto FALSE for all its channels.In all these cases, the module activates the Error LED on the front plate.Page 30 of 70HI 801 003 D Rev.2.0