IEEE 1588 clock distribution for FlexRIO devices in PXIe platforms

Abstract

In nuclear fusion environments, hundreds of thousands of data acquisition channels can be used. The time synchronization of these channels is crucial to obtaining a proper temporal correlation among the samples of all of the channels. Timestamping is the typical method used to provide a time reference to the samples. At present, the most accurate way to synchronize distributed data acquisition systems is to use the Precision Time Protocol (PTP) IEEE 1588 2008 standard, or its enhanced version, White Rabbit. The main problems related to this solution arise when the system controller in a chassis with more than one data acquisition (DAQ) device has to assign (a) timestamps to the concrete waveform samples acquired by each DAQ or has to (b) timestamp events generated by each DAQ under special conditions. One of the solutions adopted by ITER to implement the Fast Controller prototype consists of a controller device connected to a PXIe chassis with the NI-6682 timing card as the Timestamp generator and the FlexRIO devices as the DAQs. To solve this problem, a solution has been designed that distributes the clock from the IEEE 1588 timing card to all FlexRIO devices. Each DAQ device with its own clock is synchronized at every moment with the IEEE 1588 protocol, which has the capacity to assign timestamps to every sample acquired and to register events by hardware in a deterministic way. This solution increases the functionality of the NIRIO EPICS Device Support and can be included with the nominal device support that is a generic EPICS driver for every device type in the CODAC CORE System (CCS).