The internal structure of a typical LRU block shown in Fig. 11 and 12. The power supply converts voltage electricity network PC 115 VAC or 28 VDC to degraded 5 V and 15 VDC to power the microprocessor technology.
Fig. 11. Internal structure of LRU
Typical LRU block contains one input and one output digital entrance channel of information exchange with other systems and blocks of LRU (eg, ARINC 429). In order to communicate with sensors LRU can have a certain number of analog inputs and outputs with connectors for receiving digital signals and one-time transfer commands. Computing processor receives data from the module input information, handles it in accordance with laid down in the program and it gives results in processing modules forming the initial information and puts it into the internal memory.
Fig. 12. Functional structure of LRU
Each LRU has its own built-in diagnostics that in case of a malfunction in the operation of the block issues an single command failure. To maintain a certain temperature in order to reduce heating some blocks equip certain specialized ventilation equipment, as shown in Fig. 11.