<p>The paper deals with the rejection of electromagnetic relays, drawing up a block diagram with replacement by microelectronic optorelays, development of a microprocessor control unit consisting of HMI microelectronic elements for single shunting traffic lights. The circuit diagram of the block was analyzed and it was determined which elements should be replaced by which microelectronic devices. In the block containing 5 relay circuits, the electrical circuits were investigated according to the direction of movement of currents when the relay transitions to the operating state. Analysis of the operation of the block instead of a push-button relay powered by the HMID unit, as well as the calculation of the allowable current intensity showed the necessity of using in this circuit an optorelay of the PVG-612 type. As a result of the research it was possible to obtain two DGUs and create a virtual model of the block. The created unit controls both single and double shunting traffic lights.</p>