Method for identifying bus nodes in a bus system

A method for identifying bus slaves in a serial data bus system in order to allocate addresses in the serial data bus system, which has a bus line, a bus master, and multiple bus slaves, wherein the bus master is connected to the bus line on a first side and the bus slaves are successively connected to the bus line on a second side of the bus master,

• wherein one of the bus slaves is a first bus slave (BS1), which is connected to a bus line closest to the bus master, and the other bus slaves are connected to a bus line upstream of the first bus slave (BS1), with respect to a direction of a bus current flowing in the bus line to the bus master,
• wherein at least two of the bus slaves are designed as addressable bus slaves to be addressed (BS2-BS8), to which one of the addresses is respectively allocated by the bus master in an addressing phase, and others of the bus slaves may be provided as standard bus slaves (BS1) with respective addresses determined prior to carrying out the addressing phase,
• wherein the bus slaves to be addressed include at least one bus slave to be addressed (BS2, BS5-BS8) of a first type and at least one bus slave to be addressed (BS3, BS4) of a second type, different from the first type,
• wherein a current measuring circuit, electrically switched in the bus line, is assigned to each of the bus slaves to be addressed (BS2, BS5-BS8) of the first type and to each of the bus slaves to be addressed (BS3, BS4) of the second type, and each of the bus slaves to be addressed (BS2, BS5-BS8) of the first type and each of the bus slaves to be addressed (BS3, BS4) of the second type has a respective addressing current source controllable by the respective bus slave to be addressed (BS2-BS8),
• wherein a first current, supplied into the bus line by the respective addressing current source of each of the bus slaves to be addressed (BS2, BS5-BS8) of the first type, flows through all current measuring circuits located in the bus line downstream of this current measuring circuit, with the exception of the current measuring circuit assigned to the respective bus slave to be addressed (BS2, BS5-BS8) of the first type,
• wherein a second current, supplied into the bus line by the respective addressing current source of each of the bus slaves to be addressed (BS3, BS4) of the second type, flows through both the current measuring circuit assigned to the respective bus slave to be addressed (BS3, BS4) of the second type and also all the current measuring circuits located in the bus line downstream of this current measuring circuit,
• wherein, to allocate the addresses to bus slaves to be addressed (BS2-BS8) of the first type and of the second type which are not yet addressed, a plurality of the identification cycles is carried out, and one of the not yet addressed bus slaves to be addressed (BS2-BS8) of the first type or of the second type is identified per identification cycle, and the identified bus slave to be addressed (BS2-BS8) of the first type or of the second type no longer participates in further identification cycles,
• wherein, per identification cycle
• in an offset adjustment:
• each of the not yet addressed bus slaves to be addressed (BS2, BS5-BS8) of the first type and each of the not yet addressed bus slaves to be addressed (BS3, BS4) of the second type measures a potential idle current of the current measuring circuit respectively assigned to it,
• in a first phase:
• the addressing current source of each of the not yet addressed bus slaves to be addressed (BS2, BS5-BS8) of the first type supplies a preselect single first current into the bus line,
• each of the not yet addressed bus slaves to be addressed (BS2, BS5-BS8) of the first type measures the bus current by the current measuring circuit respectively assigned to it, and
• the addressing current source of each of the not yet addressed bus slave to be addressed (BS3, BS4) of the second type supplies a preselect single second current into the bus line of a magnitude such that the bus current, which is detected by the current measuring circuit assigned to the respective bus slave to be addressed (BS3, BS4) of the second type, is equal to or substantially equal to a maximum current, and
• in a second phase following the first phase:
• the addressing current sources of bus slaves to be addressed (BS2, BS5-BS8) of the first type, whose assigned current measuring circuit respectively detects a bus current in the first phase, which is smaller than the maximum current or equal to or substantially equal to the maximum current, supply the first current that is increased with respect to the first phase, and
• the addressing current sources of bus slaves to be addressed (BS2, BS5-BS8) of the first type, whose assigned current measuring circuit respectively detects a bus current in the first phase which is greater than the maximum current, do not supply the first current,
• the addressing current sources of the bus slaves to be addressed (BS3, BS4) of the second type are controlled so that the bus current, which the current measuring circuit assigned to the respective bus slave to be addressed (BS3, BS4) of the second type detects, is equal to or substantially equal to the maximum current, and
• at an end of the second phase, a bus slave to be addressed (BS2-BS8) is identified among the not yet addressed bus slaves to be addressed (BS2-BS8) of the first type or of the second type, which is the bus slave to be addressed (BS2-BS8) connected to the bus line farthest away from the bus master in the relevant cycle, in that
• the bus slave to be addressed (BS2, BS5-BS8) of the first type is identified as the last connected to the bus line, in that the current measuring circuit assigned to this bus slave to be addressed (BS2, BS5-BS8) of the first type detects in the second phase a bus current, which is not increased with respect to the idle current of the offset adjustment or is not increased by more than a predeterminable threshold value with respect to the idle current of the offset adjustment, and
• the bus slave to be addressed (BS3, BS4) of the second type is identified as the last connected to the bus line, in that its respective addressing current source supplies the second current in the second phase which is equal to or substantially equal to the bus current, which the current measuring circuit, assigned to this bus slave to be addressed (BS3, BS4) of the second type, measures in the first phase.