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Hello Yogesh,<br>
<br>
you have to notice following steps:<br>
<br>
- If you want to do DC, you have to use a RT-kernel and a
RT-application, because jitter on the base system can be a sync problem.<br>
<br>
- Do not use NTP on the system, use CLOCK_MONOTONIC or
CLOCK_MONOTONIC_RAW if accessible to get a stable clocksource.<br>
<br>
- Get system time just before you set the application time, to get the
correct time.<br>
<br>
- Sync slaves every transmit cycle.<br>
<br>
- Rise up the cycle freq, the DC syncs better if you have faster
transmit cycles<br>
<br>
- your second question: see doc under page 27- > watch -n0
"ethercat reg read -p4 -tsm32 0x92c"<br>
<br>
<br>
<br>
Best regards<br>
<br>
Andreas<br>
<br>
Am 19.05.2011 08:59, schrieb Dhake, Yogesh:
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<p class="MsoNormal"><font face="Times New Roman" size="3"><span
style="font-size: 12pt;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Hi<font color="navy"><span
style="color: navy;">,</span></font><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">EtherCAT master performs
DC synchronization as below:<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">1)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Initially
EtherCAT master calculates Propagation delay time between slaves.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">2)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Time Delay
calculated (actual frame send from Master state machine - application
start time) and deducted from System Time read from slave. New Offset
time (new offset = old offset from slave + time difference between
Master Application Start Time and Slave System Time) is send to slaves.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">3)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">After
this, Master sends synchronization datagram (with command FRMW-First
READ MULTIPLE WRITE) to reference clock slave as well as to other
EtherCAT slaves on network.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">4)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">FRMW
command reads reference clock slave system time (lower 32 bit) (0x0910
to 0x0927) and writes to lower 32 bit of other EtherCAT slave system
time register (0x0910 to 0x0927).<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">5)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Activity
number 2 to 4 happens at every 10ms in user application.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">6)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Our
observation is difference between master time and slave system time is
around 16-20 seconds after step 2.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">7)<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Slave
System Time is not accessible to us for checking whether Slave System
Time synchronized with Master Application Time.
<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Our query
is:<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 1.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">1.<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">How can we
reduce difference between Master Application Time and Slave System Time
in step 2?<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 1.5in; text-indent: -0.25in;">
<!--[if !supportLists]--><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><span style="">2.<font
face="Times New Roman" size="1"><span
style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none;">
</span></font></span></span></font><!--[endif]--><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">How to
check System Time register of BECKHOFF slave after step 4?<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Please let
us know your valuable inputs regarding synchronization of Distributed
clocks of EtherCAT slaves.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Please
find attached DC synchronization process. Rename file to .png type.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Regards,<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;">Yogesh<o:p></o:p></span></font></p>
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<pre class="moz-signature" cols="72">Mit freundlichem Gruß
Andreas Stewering-Bone
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