Method for digital communication between at least one first node being a master node or a node in a master mode and a plurality of second nodes respectively being a slave node or a node in a slave mode and which are connected with the first node by a serial field bus supporting different physical field bus levels for representing logical values comprising logical ones and logical zeros of bits making up digital messages which are sent via the field bus, a1) wherein a respective node (18; 20), for sending a digital message via said field bus to at least one other node (20; 18), time-dependently manipulates the field bus, so that time-dependently assumed physical field bus levels represent the bits of said digital message, A2) wherein the nodes (18; 20), for reading digital messages sent via said field bus, detect time-dependently assumed physical field bus levels to read bits of a respective message, A3) wherein the second nodes are adapted to respond to predetermined digital messages read by sending a respective response message, wherein the method provides a first mode of digital communication between said nodes (18; 20) via said field bus and a second mode of digital communication between said nodes (18; 20) via said field bus, wherein the second mode of digital communication is based on message priorities of digital messages to be sent by a respective second node to the first node via said field bus, wherein the first mode of digital communication is not based on message priorities and provides at least one of an alternate communication path for digital messages to be sent by a respective second node to the first node via said field bus and presence detection mechanism by which the first node determines which of said second nodes are operational to communicate with the first node via said field bus, wherein the first node sends a digital broadcast polling message of first type starting the communication according to the first mode of digital communication and a digital broadcast polling message of second type starting the second mode of digital communication subsequently according to a polling schedule, which involves in turn to send said digital broadcast polling message of second type at least once and subsequently to send said digital broadcast polling message of first type and to read the respective response message or response messages from said second nodes from the field bus after each digital broadcast polling message of respective first or second type according to the respective first or second communication mode before the next digital broadcast polling message of respective first or second type is sent. a1) wherein a respective node (18; 20), for sending a digital message via said field bus to at least one other node (20; 18), time-dependently manipulates the field bus, so that time-dependently assumed physical field bus levels represent the bits of said digital message, A2) wherein the nodes (18; 20), for reading digital messages sent via said field bus, detect time-dependently assumed physical field bus levels to read bits of a respective message, A3) wherein the second nodes are adapted to respond to predetermined digital messages read by sending a respective response message,