[etherlab-users] distributed clocks query

Paul Mulligan mulligan252 at yahoo.ie
Tue Mar 1 12:44:30 CET 2016


Hi,
I'm still unsure as to what values are given for the last four parameters of this function. I believe the sync1_cycle and sync1_shift can be ignored but how is the sync0_shift value determined? I believe the frame should reach all the slaves before this time but also the new frame should not be received before this time. In the examples given, a scan time of 1ms is used but the sync0_shift value is 4.4 ms. How can this be correct?
ecrt_slave_config_dc(modules[index].sc, 0x0300, scanTime, ??, ??, ??, ??); 

    On Monday, 29 February 2016, 15:57:30, Richard Hacker <ha at igh.de> wrote:
 

 I only configure DC on the slaves that are actually required to be 
synchronized.

Otherwise it seems correct what you are doing...

Am 2016-02-29 um 14:45 schrieb Paul Mulligan:
> Hi,
>
> Just a question or two about distributed clocks.
>
> I have a system with an EL1008 digital input module, EL3001 analogue
> input module, two EL7031 stepper motor driver modules and two EL2008
> digital output modules in that order. I am using the EK1100 bus coupler
> terminal as the first module.
>
> Do I need to call ecrt_slave_config_dc() for all of these modules before
> activating the master, or just the first module on the bus? My
> understanding from reading about distributed clocks is that the first
> module on the bus with DC capability should be used as the reference clock.
>
>  From looking at the example "dc_user" supplied in the master download,
> it calls ecrt_slave_config_dc() only for the IDS_COUNTER module.
>
> In the cyclic_task(), the functions ecrt_master_application_time(),
> ecrt_master_sync_reference_clock(), ecrt_master_sync_slave_clocks() are
> then called in that order. I notice ecrt_master_reference_clock_time()
> is not used at all here.
>
> Is this all that is required to control the distributed clocks ? Thank
> you in advance.
>
>
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