US 2005/0232384 A1Published application

Method for the synchronization of subscribers of a network

AssigneeJetter AG

InventorsAndreas Heid, Andreas Kraut, Steffen Schwips

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Abstract

According to the invention, a time emitter of a subscriber (1) provided as a reference in a network regularly and/or randomly transmits reference time signals (TR1). A subscriber (2) approximately adjusts the local time measurement thereof in relation to the time measurement of the reference subscriber (1) only if the difference between the reference time (TR) and local time (TL) is less than a predetermined or predeterminable threshold value (e), at the moment when the reference time signal is received and/or a signal path is kept clear between the subscriber (2) and the reference subscriber (1) or the network for instantaneous data transmission.

Claims14

Dependent claims

a subscriber (2) correcting its local time measurement for adaptation to the time measurement of the reference subscriber or server (1) only when the difference between reference time (TR) and local time (TL), at the instant of reception of the reference time signal, is smaller in magnitude than a predefined or predefinable threshold value (ε) and/or a signal path between subscriber (2) and reference subscriber or server (1) or the network is kept free for delay-free data communication. characterized
in that the time measurement of processors of a process control network is corrected by adapting the speed of the local timer of the respective processor in accordance with the difference between the reference time and the local time that is to be taken into account.

A method for the synchronization of local timers of subscribers (2) of a network, with a timer of a subscriber or server (1) that is predefined or predefinable as a reference in the network, which regularly and/or stochastically transmits reference time signals (TR1) or data packets comprising such signals, it being possible for unforeseeably variable data transmission times to occur in the network, inter alia caused by varying loading and/or an altered structure of the network and of its subscribers, in particular at network nodes, and/or varying signal paths, a subscriber (2) correcting its local time measurement for adaptation to the time measurement of the reference subscriber or server (1) only when the difference between reference time (TR) and local time (TL), at the instant of reception of the reference time signal, is smaller in magnitude than a predefined or predefinable threshold value (ε) and/or a signal path between subscriber (2) and reference subscriber or server (1) or the network is kept free for delay-free data communication. characterized

in that the reference subscriber or server (1) transmits to a subscriber (2), at a first instant (TR1), a time signal (GONG STROKE signal) and subsequently a data packet with the reference time (TR1)
in that the subscriber detects the local instant (TL1) of reception of the GONG STROKE signal and transmits an echo of the GONG STROKE signal to the reference subscriber or server at a later local instant (TL2),
in that the reference subscriber or server (1) detects the instant (TR2) of reception of the echo,
in that the sum of the difference between the first-mentioned local instant (TL1) and the first-mentioned reference instant (TR1) and the difference between the latter reference instant (TR2) and the later local instant (TL2) is determined,
in that a check is made to determine whether the magnitude of said sum lies below a small threshold value (ε), and
in that it is only when this condition is met that the local time measurement of the subscriber (2) is approximated or matched to the time measurement of the reference subscriber or server.

3 more elements

Dependencies are inferred from the claim text.