Re: [etherlab-users] DC questions
Hi,
Try having a look at:
https://www.mail-archive.com/etherlab-users@etherlab.org/msg02641.html
The post above shows the general flow of my program.
I use RTAI. Below are the structures and functions I currently use to sync the
master to the slave reference master. I think there's also some other versions
out there in past forum posts.
Some of the structures used:
struct _etherCATModule_s
{
...
ec_master_t*master; /**< the ethercat master
reference once attached */
ecDevice_s *m_dcRefSlave; /**< is there a configured ref
slave? */
uint64_tm_dcTimeStart;/**< distributed clock first
now time */
uint64_tm_dcTime; /**< distributed clock now time
*/
int32_t m_dcDiff; /**< distributed clock master
to ref slave diff time */
bool_t m_getDCDiff; /**< we are ready to get the
distributed clock diff time */
...
};
/** the global application data structure
*/
typedef struct _app_s
{
...
uint64_t scanTimeNS; /**< the amount of time per
scan in nanoseconds */
uint64_t scanTimeMS; /**< the amount of time per
scan in milliseconds */
doublescanTimeSec; /**< the amount of time per
scan in seconds */
int32_t rtTimeDiff; /**< master time source time
diff (ns) */
int32_t rtTimeDelta; /**< master time source time
diff delta (ns) */
uint64_t rtTimeStart; /**< master time source time
base start (ns) */
uint64_t rtTimeCurr; /**< master time source time
base current (ns) */
int64_t rtAdjBy; /**< master time source cycle
adjustment value (ns) */
uint64_t nextWakeTime;/**< next cycle wake time time
(ns) */
uint64_t actualWakeTime; /**< actual cycle wake time
(ns) */
uint64_t overruns;/**< the number of overruns
that have occured */
...
} app_s;
When preparing to run:
intecRes;
ec_slave_config_t *refSlaveConfig = NULL;
// set up distributed clocks
ecMod->m_dcTimeStart = app_getTimeNS();
ecMod->m_dcTime = ecMod->m_dcTimeStart;
if (ecMod->m_dcRefSlave)
{
refSlaveConfig = ecMod->m_dcRefSlave->slaveConfig;
}
// set initial app time (time must be in phase with realtime cycle)
ecrt_master_application_time(ecMod->master, ecMod->m_dcTimeStart);
// select the slave device to be the reference clock
ecRes = ecrt_master_select_reference_clock(ecMod->master, refSlaveConfig);
if (ecRes < 0) return E_EC_ACTIVATE_ERROR;
// activate the master
ecRes = ecrt_master_activate(ecMod->master);
if (ecRes < 0) return E_EC_ACTIVATE_ERROR;
The "sync distributed clock" function is something like:
int32_t ecMod_syncDistClock(
void *this/**< pointer to module etherCATModule_s */
)
{
etherCATModule_s *ecMod = this;
uint32_t masterTime;
// cache lower 32 bits of prev master time and get now
masterTime = (uint32_t)ecMod->m_dcTime;
ecMod->m_dcTime = app_getTimeNS();
// use the dc ref slave to adjust the masters time base
// get lower 32 bit of clock time from reference slave (after first scan)
if (ecMod->m_getDCDiff)
{
int res;
uint32_t slaveTime;
res = ecrt_master_reference_clock_time(ecMod->master, );
switch (res)
{
case 0 :
{
// calc time diff
ecMod->m_dcDiff = masterTime - slaveTime;
} break;
default :
{
// no ref clock found or datagram failure
ecMod->m_dcDiff = 0;
}
}
}
else
{
ecMod->m_dcDiff= 0;
ecMod->m_getDCDiff = true;
}
// call to sync slaves to ref slave
// (which is used for ecrt_master_reference_clock_time)
ecrt_master_sync_slave_clocks(ecMod->master);
// update the master time for the next cycle (in nano-seconds)
// (this is required for the master to figure out the modules initial
// dc time)
ecrt_master_application_time(ecMod->master, ecMod->m_dcTime +
g_app.scanTimeNS);
return 0;
}
The "calc slave to master time drift and adjust master clock and cycle period to
match" function is:
#define DC_FILTER_CNT 1024
static bool_t u_dcStarted = false;
static int32_t u_dcLastDiff = 0;
static int64_t u_dcDiffTot = 0LL;
static int64_t u_dcDeltaTot = 0LL;
static int u_dcIdx = 0;
/** update the master time based on ref slaves time diff
*
* called after the ethercat frame is sent to avoid time jitter in
* ecMod_syncDistClock()
*/
int32_t ecMod_updateMasterClock(
void *this/**< pointer to module module_s */
)
{
etherCATModule_s *ecMod = this;
assert(ecMod->master);
if (u_dcStarted)
{
// calc drift (via un-normalised time diff)
[etherlab-users] ethercat absolut encoders
Hey there, Anybody are interested in a absolute ethercat encoder?, I have two, It was purchased for a hexpod project but it was no going. Best regards Javier Gomez ___ etherlab-users mailing list etherlab-users@etherlab.org http://lists.etherlab.org/mailman/listinfo/etherlab-users
[etherlab-users] Detect the loss of EtherCAT communication
Hi All, is there any other way for a slave to detect a failure of EtherCAT communication besides the syncmanager watchdogs e.g. connection loss between 2 slaves or a failure of the user application? The syncmanager watchdog only works for buffered mode but not for mailbox mode which has acyclic communication. Background: our slaves will use mainly mailbox communication (VoE) which is most suitable for our purpose. We solved this problem by introducing a status byte as PDO which also has a watchdog configured. I am still eager to know if there is some other possibility for a slave to detect missing EtherCAT communication. Thanks and best regards, Christoph Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V. Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv. Vorsitzende Dr. Beatrix Vierkorn-Rudolph Geschäftsführung: Prof. Dr. Anke Rita Kaysser-Pyzalla, Thomas Frederking Sitz Berlin, AG Charlottenburg, 89 HRB 5583 Postadresse: Hahn-Meitner-Platz 1 D-14109 Berlin http://www.helmholtz-berlin.de ___ etherlab-users mailing list etherlab-users@etherlab.org http://lists.etherlab.org/mailman/listinfo/etherlab-users
[etherlab-users] R: DC questions
Thank you both for your answers. I would like to get again your help in order to find a little example, focused only on the synchronization part, for the b method introduced by Graeme, because I have already tried something but the application continuosly sends the "Failed to get reference clock time: Input/Output error" error. Thank you again. Best regards, Tommaso ___ etherlab-users mailing list etherlab-users@etherlab.org http://lists.etherlab.org/mailman/listinfo/etherlab-users
