https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/INSTRM-149 Instrument control development <p>These days, Linux includes decent PTP support, and PTP can be used in place of NTP. Do we want to? The underlying question is whether we will ever need instrument-wide timing better than a few milliseconds.</p> <p>The one obvious problem which could benefit from precise relative instrument-wide timing is matching fiber motion or LED strobes to MCS rows. If there is any chance we will want to synchronize those I believe we should use PTP. If not, NTP is fine.</p> <p>I don't think there is a significant difference in management effort these days. The head server can use the observatory NTP feed for its absolute time, regardless of the chosen protocol.</p> INSTRM-149

Choose between NTP and PTP

Task Normal Done Done Unassigned cloomis Wed, 12 Jul 2017 16:33:00 +0000 Fri, 17 Mar 2023 21:21:08 +0000 Fri, 17 Mar 2023 21:21:08 +0000 0 5 <p>Subaru provides NTP over their summit network, under their stratum 1 from GPS.<br/> I am not sure they can proveide PTP to us, but it is definitely important for us to have (some) precise timestamp, even if it is not synced to precise time, so let the project office to discuss/propose something to subaru (next week - week of 17th 07/2017).</p> <p>We need to get time from Subaru via NTP from stratum 2 NTP server at summit. I'd vote to have both NTP and PTP if we really want to have PTP in PFS ICS, since some hardware, including UPS, need NTP but not support PTP.</p> <p>One concern for using PTP for timing of LED strobes is how we can use. Two light sources (FFIS in PFI, BIA in SpS) is controlling LED driver by GPIO of ethernet connected Arduino. Commanding to Arduino are done by remote computer (actor), CB2F for FFIS, SpS/5th rack for BIA, and there are some uncertain latency from commanding actor and hardware. Also it would be quite difficult to have PTP like timing software in Arduino.</p> <p>I don't care about UPS time, but for subsystems that we care about I really don't think we want two time protocols to get out of sync (although we could add a component to check for that, I suppose, and warn)</p> <p>It appears that arduinos do support PTP (but Shimono-san and Craig are the experts); <a href="https://forum.arduino.cc/index.php?topic=348881.0" class="external-link" rel="nofollow">https://forum.arduino.cc/index.php?topic=348881.0</a> says that</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"> $ opkg list | grep ptpd returns: ptpd - 2.1.0-2 - The PTP daemon (PTPd) <span class="code-keyword">implements</span> version 2 of the Precision Time Protocol (PTP) as defined by the IEEE 1588-2008 standard. PTP was developed to provide very precise time coordination of LAN connected computers. </pre> </div></div> <p>I don't think Arduino Ethernet can run OpenWrt... Yun could be, which has processor and microcontroller.</p> <p>the answer is NTP</p> Blocks INSTRM-291 Development Rank 0|ii02g7: