HIMax Safety Manual - Tuv-fs.com

8 Output Modules HIMaxIn this state, the outputs are checked every few seconds to determine wether the overloadis still present. In a normal state, the outputs are switched back on.NOTICESystem malfunction possible!The voltage induced during switching off inductive loads could cause faults in thecontroller or in other electronical systems close to the actor's input leads.Therefore, it is a good practice to connect inductive loads with a suitable freewheelingcircuit at the actuator, to counteract these disturbances.8.6 Safety-Related Relay OutputsRelay output cards are connected to the actuator under any of the following circumstances:• Electric isolation is required.• Higher amperages are used.• Alternating currents are to be connected.The module outputs are equipped with two safety relays with forcibly guided contacts. Theoutputs can thus be used for safety shutdowns in accordace with SIL 3.Furthermore, the watchdog signal of the module provides a second means of safetyshutdown: If the watchdog signal is lost, the module immediately adopts the safe state.8.6.1 Use of Digital Relay OutputPerform the following steps to write a value in the user program to a digital relayoutput:1. 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 output.The global variable provides the safe value to the digital output.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.8.6.2 Test Routines for Relay OutputsThe module is tested automatically during operation.The main test functions are:• Reading the output signals back from the switching amplifiers located before the relays• Testing the switching of the relays with forcibly guided contacts• Checking the integrated redundant safety shutdown.8.6.3 Reaction in the Event of a FaultIf a faulty signal is detected, the affected module output is set to the safe, de-energizedstate using the safety switches. If a module fault occurs, all module outputs are switchedoff. Both types of faults are also indicated by the Error LED.Page 42 of 70HI 801 003 D Rev.2.0