[etherlab-users] Distributed Clocks
Thomas Bitsky Jr
tbj at automateddesign.com
Mon Feb 22 04:23:27 CET 2016
Ok, after following all your advice, plus the clock adjustment from Mattieu, I’m pretty close. I enable the DC on the drive, get everything into op, the domains all come up and it would appear that the clocks are syncing. Except for one thing:
[10248.633619] EtherCAT 0: Domain 0: Working counter changed to 1/17.
[10249.535776] EtherCAT WARNING 0: 3989 datagrams UNMATCHED!
[10249.539861] EtherCAT WARNING: Datagram f3bf2d0c (domain0-0-main) was SKIPPED 1 time.
[10249.539887] EtherCAT WARNING: Datagram f3bf2a8c (domain2-120-main) was SKIPPED 1 time.
[10249.539918] EtherCAT WARNING: Datagram f3bf2e8c (domain1-114-main) was SKIPPED 1 time.
[10249.635934] EtherCAT 0: Domain 0: 9 working counter changes - now 17/17.
[10249.919163] EtherCAT 0: Domain 2: Working counter changed to 1/1.
[10250.018245] EtherCAT 0: Domain 1: Working counter changed to 1/1.
[10250.040259] EtherCAT 0: Slave states on main device: OP.
[10250.536654] EtherCAT WARNING 0: 4001 datagrams UNMATCHED!
[10251.537469] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10252.538282] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10252.538296] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10253.539097] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10254.539909] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10255.540723] EtherCAT WARNING 0: 4000 datagrams UNMATCHED!
[10256.541537] EtherCAT WARNING 0: 4000 datagrams UNMATCHED! <— This continues indefinitely
Everything else seems okay:
user at core:~/dist$ ethercat slaves
0 0:0 OP + EK1100 EtherCAT-Koppler (2A E-Bus)
1 0:1 OP + EL1104 4K. Dig. Eingang 24V, 3ms, Sensorversorgung
2 0:2 OP + EL1104 4K. Dig. Eingang 24V, 3ms, Sensorversorgung
3 0:3 OP + EL5101 1K. Inc. Encoder 5V
4 0:4 OP + EL7041 1K. Schrittmotor-Endstufe (50V, 5A)
5 0:5 OP + EL7041 1K. Schrittmotor-Endstufe (50V, 5A)
6 0:6 OP + EL2004 4K. Dig. Ausgang 24V, 0.5A
7 0:7 OP + EL2004 4K. Dig. Ausgang 24V, 0.5A
8 0:8 OP + EL4001 1K. Ana. Ausgang 0-10V, 12bit
9 1:0 OP + 0x00000539:0x02200001
user at core:~/dist$ ethercat master
Master0
Phase: Operation
Active: yes
Slaves: 10
Ethernet devices:
Main: 00:30:18:c8:d4:92 (attached)
Link: UP
Tx frames: 5204542
Tx bytes: 733318966
Rx frames: 5204539
Rx bytes: 733318636
Tx errors: 0
Tx frame rate [1/s]: 4000 3944 2090
Tx rate [KByte/s]: 823.7 811.9 412.9
Rx frame rate [1/s]: 4000 3944 2090
Rx rate [KByte/s]: 823.7 811.9 412.9
Common:
Tx frames: 5204542
Tx bytes: 733318966
Rx frames: 5204539
Rx bytes: 733318636
Lost frames: 3
Tx frame rate [1/s]: 4000 3944 2090
Tx rate [KByte/s]: 823.7 811.9 412.9
Rx frame rate [1/s]: 4000 3944 2090
Rx rate [KByte/s]: 823.7 811.9 412.9
Loss rate [1/s]: 0 0 0
Frame loss [%]: 0.0 0.0 0.0
Distributed clocks:
Reference clock: Slave 0
Application time: 509424243322706771
2016-02-22 02:44:03.322706771
I must have something out of sync. Is there something more I’m supposed to do to adjust the clock? I can make the number of dropped packets worse by simplifying the time adjustment, but I can’t seem to get it any better. I think I’m not understanding something about the clock adjustment. Can you see what I’m doing wrong?
Thanks!
My cyclic task:
static void
sync_distributed_clocks(void)
{
uint32_t ref_time = 0;
uint64_t prev_app_time = dc_time_ns;
dc_time_ns = system_time_ns();
// set master time in nano-seconds
ecrt_master_application_time(master_, dc_time_ns);
// get reference clock time to synchronize master cycle
ecrt_master_reference_clock_time(master_, &ref_time);
dc_diff_ns = (uint32_t) prev_app_time - ref_time;
// call to sync slaves to ref slave
ecrt_master_sync_slave_clocks(master_);
}
static unsigned int cycle_ns = 1000000; // 1 millisecond
void update_master_clock(void)
{
// calc drift (via un-normalised time diff)
int32_t delta = dc_diff_ns - prev_dc_diff_ns;
prev_dc_diff_ns = dc_diff_ns;
// normalise the time diff
dc_diff_ns =
((dc_diff_ns + (cycle_ns / 2)) % cycle_ns) - (cycle_ns / 2);
// only update if primary master
if (dc_started)
{
// add to totals
dc_diff_total_ns += dc_diff_ns;
dc_delta_total_ns += delta;
dc_filter_idx++;
if (dc_filter_idx >= DC_FILTER_CNT)
{
// add rounded delta average
dc_adjust_ns +=
((dc_delta_total_ns + (DC_FILTER_CNT / 2)) / DC_FILTER_CNT);
// and add adjustment for general diff (to pull in drift)
dc_adjust_ns += sign(dc_diff_total_ns / DC_FILTER_CNT);
// limit crazy numbers (0.1% of std cycle time)
if (dc_adjust_ns < -1000) {
dc_adjust_ns = -1000;
}
if (dc_adjust_ns > 1000) {
dc_adjust_ns = 1000;
}
// reset
dc_diff_total_ns = 0LL;
dc_delta_total_ns = 0LL;
dc_filter_idx = 0;
}
// add cycles adjustment to time base (including a spot adjustment)
system_time_base += dc_adjust_ns + sign(dc_diff_ns);
}
else
{
dc_started = (dc_diff_ns != 0);
if (dc_started)
{
// output first diff
PRINT("First master diff: %d.\n", dc_diff_ns);
// record the time of this initial cycle
dc_start_time_ns = dc_time_ns;
}
}
}
int
ecatMain_process(void* lp)
{
sync_distributed_clocks();
update_master_clock();
ecrt_master_receive(master_);
ecrt_domain_process(lrwDomainMgr_.domain);
ecrt_domain_process(noLrwWriteDomainMgr_.domain);
ecrt_domain_process(noLrwReadDomainMgr_.domain);
… // handle my business
// send process data
ecrt_domain_queue(lrwDomainMgr_.domain);
ecrt_domain_queue(noLrwWriteDomainMgr_.domain);
ecrt_domain_queue(noLrwReadDomainMgr_.domain);
// send EtherCAT data
ecrt_master_send(master_);
return 1;
}
I made my sync0 time half of the can rate, as you prescribed:
void
ecatModule_registerDcClock( Slave* slave, uint16_t addr )
{
struct timespec cur_time;
clock_gettime(CLOCK_REALTIME, &cur_time);
uint16_t sync0time = (uint16_t)((globalScanRate_us * 1000) / 2);
ecrt_slave_config_dc(
slave->sc,
addr,
(globalScanRate_us * 1000),
sync0time,
0,
0);
}
From: Graeme Foot <Graeme.Foot at touchcut.com<mailto:Graeme.Foot at touchcut.com>>
Date: Sunday, February 21, 2016 at 4:07 PM
To: Thomas Bitsky <tbj at automateddesign.com<mailto:tbj at automateddesign.com>>
Cc: "etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>" <etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>>
Subject: RE: Distributed Clocks
Hi,
I build and patch against revision 2526, so don’t know what patches / fixes have made it through to the latest release. However for my revision I need fixes for reference clock selections and dc synchronization issues.
I’ve attached the dc related patches I use, but these are applied after some other patches so you may get some conflicts or offsetting.
01 - Distributed Clock fixes and helpers.patch
This sorts out some ref slave issues, allowing a user selected ref slave. It also adds some helper functions:
- ecrt_master_setup_domain_memory() : this allows me to set up the domain memory and do stuff with it before calling ecrt_master_activate() (for user space apps)
- ecrt_master_deactivate_slaves() : this lets me deactivate the slaves while still in realtime to avoid the slaves getting some shutdown sync errors
02 - Distributed Clock fixes from Jun Yuan - dc sync issues.patch
This sorts out some timing issues to do with slave dc syncing. Without it they can start syncing from one cycle out causing a large syncing time overhead, one slave at a time.
Regards,
Graeme.
From: Thomas Bitsky Jr [mailto:tbj at automateddesign.com]
Sent: Sunday, 21 February 2016 10:27 a.m.
To: Graeme Foot
Cc: etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
Subject: Re: Distributed Clocks
Graeme,
Thank you so much for the detailed response. I'm away from my computer right now, so I can't try out your advice, but I noticed you asked about patches. I am not running any patches; which should I get?
Thanks!
Thomas Bitsky Jr
On Feb 20, 2016, at 3:04 PM, Graeme Foot <Graeme.Foot at touchcut.com<mailto:Graeme.Foot at touchcut.com>> wrote:
Hi,
The slave clocks get synced via the distributed clock system using the master methods: ecrt_master_reference_clock_time(), ecrt_master_sync_slave_clocks(), ecrt_master_application_time(), ecrt_master_sync_reference_clock().
However each individual slave can choose (if it is capable of it) whether to synchronize its reading and writing of data to a particular point in time within the dc cycle. If that slave does not choose to do so then the reading and writing of the data occurs at the time the EtherCAT frame goes past, resulting in a progressive update and application of data as the frame progresses through all of the slaves.
If a slave is registered to use the dc clock then it caches the frame data until the sync0 interrupt so in theory all dc slaves apply the data at the same time. It also means you don’t have to worry about jitter as to the time the frame is sent over the wire. The only thing is to choose a good sync0 time to ensure your frames are always sent out and have reached all of the slaves before the sync0 time occurs, and that the next frame is not sent out before the previous sync0 time occurs.
In my application my cycle time is 1000us. I choose a sync0 time of 500us. I also send my frame as close as possible to the beginning of the cycle. This gives the frame up to half the cycle time to reach all of the slaves and then the other half of the cycle for the frame to return in time for the master receive call. I could choose a sync0 time later than 500us but I want it processed as soon as possible after the frame is received while still allowing for a bus with a large number of terminals.
So below where you are calculating loop_shift based on the current time is wrong. Just choose a time within the dc cycle and use that value for all slaves. Note: the beginning of the dc cycle is in phase with the first call to ecrt_master_application_time(), so all of your realtime looping should also be in phase with that initial time.
Note, when selecting a slave to be the DC reference slave you should generally choose the first slave on your bus, regardless of whether it will be (or can be) registered to use the dc synchronization. At the very least it must be before, or be the, first slave that will be registered as a dc slave.
Also note that some slaves clocks are not very stable and shouldn’t be used as the DC reference slave. My original testing was on a Beckhoff CX1020 with a CX1100-0004, this could not be used as a reference slave as its clock was not stable.
I see you are configuring the slaves via ecrt_slave_config_*() then calling ecrt_slave_config_pdos() at the end. If you call ecrt_slave_config_pdos() at the beginning you don’t need all the other config calls. However I hear AKD drives and some other slaves prefer explicit slave config calls but most slaves are happy with just the ecrt_slave_config_reg_pdo_entry() methods.
This also leads to another issue. One of the configured PDO items is the “mode of operation” value (0x6060 0x00). You are also configuring this with: ecrt_slave_config_sdo8( sc, 0x6060, 0, 8 ). This value should be instead be set via the PDO value. Use ecrt_slave_config_reg_pdo_entry() to get the offset to the value and set the value there.
Sorry if that was a bit long but DC’s is not an easy topic to get your head around. Here’s a bit of a summary:
- You can choose which slaves get registered with ecrt_slave_config_dc(). But each slave you want synced must get its own call to ecrt_slave_config_dc().
- If your yaskawa drives get to OP without ecrt_slave_config_dc()then they should get to OP with ecrt_slave_config_dc().
- The yaskawa drives require a very stable reference slave time, which is why we sync the EtherCAT master to the reference slave rather than the other way around.
And some other comments:
- Never use anEL9010 endcap module. These break the distributed clock calculations. I don’t think they are available anymore though.
- There are some patches out there that fix various DC clock issues, are you using any of these?
Regards,
Graeme.
From: Thomas Bitsky Jr [mailto:tbj at automateddesign.com]
Sent: Sunday, 21 February 2016 7:15 a.m.
To: Graeme Foot; etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
Subject: Re: Distributed Clocks
[snip]
I’ve never been able to get the EL7041 stepper modules to work in dc mode.
[/snip]
Is it all or nothing? I need the servo drives, the LVDT and the EL3356 tied to a distributed clock. The EL7041 is optional for me.
[snip]
I don’t see in your code calls to ecrt_slave_config_dc().
For the yaskawa drive, during the config stage, I use the following calls…
[/snip]
Forgot to put that part; my bad. This is what I had for the Yaskawa/AKD, although I was only doing it to one of the drives. I thought I was supposed to set up one distributed clock, and it became the master and handled the rest. Am I supposed to do this for all the cards, or do I select?
Yaskawa(AKD drive code is pretty much the same):
if (!(sc = ecrt_master_slave_config(
master,
slavePosDomain,
slavePosIndex,
vendorId, productCode)))
{
return FALSE;
}
ecrt_slave_config_sdo8( sc, 0x1C12, 0, 0 ); /* clear sm pdo 0x1c12 */
ecrt_slave_config_sdo8( sc, 0x1C13, 0, 0 ); /* clear sm pdo 0x1c12 */
ecrt_slave_config_sdo8( sc, 0x1A00, 0, 0 ); /* clear TxPDO0 */
ecrt_slave_config_sdo8( sc, 0x1A01, 0, 0 ); /* clear TxPDO1 */
ecrt_slave_config_sdo8( sc, 0x1A02, 0, 0 ); /* clear TxPDO2 */
ecrt_slave_config_sdo8( sc, 0x1A03, 0, 0 ); /* clear TxPDO3 */
ecrt_slave_config_sdo8( sc, 0x1600, 0, 0 ); /* number of var in this PDO */
ecrt_slave_config_sdo8( sc, 0x1601, 0, 0 ); /* clear RxPdo 0x1601 */
ecrt_slave_config_sdo8( sc, 0x1602, 0, 0 ); /* clear RxPdo 0x1602 */
ecrt_slave_config_sdo8( sc, 0x1603, 0, 0 ); /* clear RxPdo 0x1603 */
ecrt_slave_config_sdo8( sc, 0x1A00, 0, 0 ); /* clear TxPDO0 */
ecrt_slave_config_sdo32( sc, 0x1A00, 1, 0x60410010 ); // Status word
ecrt_slave_config_sdo32( sc, 0x1A00, 2,0x60640020 );// Position actual value, per encoder
ecrt_slave_config_sdo32( sc, 0x1A00, 3,0x60770010 );// Torque, actual value
ecrt_slave_config_sdo32( sc, 0x1A00, 4,0x60F40020 );// Following error, actual value
ecrt_slave_config_sdo32( sc, 0x1A00, 5,0x60610008 );// Modes of operation display
ecrt_slave_config_sdo32( sc, 0x1A00, 6,0x00000008 );// GAP
ecrt_slave_config_sdo32( sc, 0x1A00, 7,0x60B90010 );// Touch probe status
ecrt_slave_config_sdo32( sc, 0x1A00, 8, 0x60BA0020 ); // Touch probe 1 position
ecrt_slave_config_sdo8( sc, 0x1A00, 0, 8 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1A01, 0, 0 ); /* clear TxPDO1 */
ecrt_slave_config_sdo32( sc, 0x1A01,1,0x60410010 ); // Status word
ecrt_slave_config_sdo32( sc, 0x1A01,2,0x60640020 );// Position actual value, per encoder
ecrt_slave_config_sdo8( sc, 0x1A01, 0, 2 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1A02, 0, 0 ); /* clear TxPDO2 */
ecrt_slave_config_sdo32( sc, 0x1A02,1,0x60410010 ); // Status word
ecrt_slave_config_sdo32( sc, 0x1A02,2,0x60640020 );// Position actual value, per encoder
ecrt_slave_config_sdo8( sc, 0x1A02, 0, 2 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1A03, 0, 0 ); /* clear TxPDO2 */
ecrt_slave_config_sdo32( sc, 0x1A03,1,0x60410010 ); // Status word
ecrt_slave_config_sdo32( sc, 0x1A03,2,0x60640020 );// Position actual value, per encoder
ecrt_slave_config_sdo32( sc, 0x1A03,3,0x60770010 );// Torque, actual value
ecrt_slave_config_sdo8( sc, 0x1A03, 0, 3 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1600, 0, 0 ); /* clear entries */
ecrt_slave_config_sdo32( sc, 0x1600, 1, 0x60400010 ); /* control word */
ecrt_slave_config_sdo32( sc, 0x1600, 2, 0x607A0020 ); /* target position */
ecrt_slave_config_sdo32( sc, 0x1600, 3, 0x60FF0020 ); /* target velocity */
ecrt_slave_config_sdo32( sc, 0x1600, 4, 0x60710010 ); /* target torque */
ecrt_slave_config_sdo32( sc, 0x1600, 5, 0x60720010 ); /* max torque */
ecrt_slave_config_sdo32( sc, 0x1600, 6, 0x60600008 ); /* modes of operation */
ecrt_slave_config_sdo32( sc, 0x1600, 7, 0x00000008 ); /* gap */
ecrt_slave_config_sdo32( sc, 0x1600, 8, 0x60B80010 ); /* touch probe function */
ecrt_slave_config_sdo8(sc, 0x1600, 0, 8 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1601, 0, 0 ); /* clear entries */
ecrt_slave_config_sdo32( sc, 0x1601, 1, 0x60400010 ); /* control word */
ecrt_slave_config_sdo32( sc, 0x1601, 2, 0x607A0020 ); /* target position */
ecrt_slave_config_sdo8( sc, 0x1601, 0, 2 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1602, 0, 0 ); /* clear entries */
ecrt_slave_config_sdo32( sc, 0x1602, 1, 0x60400010 ); /* control word */
ecrt_slave_config_sdo32( sc, 0x1602, 2, 0x60FF0020 ); /* target position */
ecrt_slave_config_sdo8( sc, 0x1602, 0, 2 ); /* pdo entries */
ecrt_slave_config_sdo8( sc, 0x1603, 0, 0 ); /* clear entries */
ecrt_slave_config_sdo32( sc, 0x1603, 1, 0x60400010 ); /* control word */
ecrt_slave_config_sdo32( sc, 0x1603, 2, 0x60710020 ); /* target position */
ecrt_slave_config_sdo8( sc, 0x1603, 0, 2 ); /* pdo entries */
ecrt_slave_config_sdo16( sc, 0x1C12, 1, 0x1601 ); /* download pdo 1C12 index */
ecrt_slave_config_sdo8( sc, 0x1C12, 0, 1 ); /* set number of RxPDO */
ecrt_slave_config_sdo16( sc, 0x1C13, 1, 0x1A01 ); /* download pdo 1C13 index */
ecrt_slave_config_sdo8( sc, 0x1C13, 0, 1 ); /* set number of TxPDO */
// OPMODE
// Yaskawa recommends 8
ecrt_slave_config_sdo8( sc, 0x6060, 0, 8 );
unsigned char interpolationTime = 0xFF;
// 250
unsigned char cycleExponent = 0xFA;
// microseconds
// globalSCanRate_us equals either 250 or 125.
unsigned int us = globalScanRate_us;
size_t i;
for ( i=0;i<6, us > 0xFF;++i )
{
us /= 10;
cycleExponent += 1;
}
interpolationTime = us;
ecrt_slave_config_sdo8( akd->sc_akd, 0x60C2, 1, interpolationTime ); /* Interpolation time */
ecrt_slave_config_sdo8( akd->sc_akd, 0x60C2, 2, cycleExponent ); /* Cycle exponent */
PRINT("Configuring PDOs...\n");
if (ecrt_slave_config_pdos(sc, EC_END, slave_syncs))
{
PRINT("Failed to configure Yaskawa Sigma PDOs.\n");
return FALSE;
}
struct timespec cur_time;
clock_gettime(CLOCK_REALTIME, &cur_time);
size_t loop_period = globalScanRate_us * 1000;
if ( loop_period == 0 ) loop_period = 1;
size_t loop_shift
= loop_period - (cur_time.tv_nsec % loop_period);
ecrt_slave_config_dc(
sc,
0x0300,
loop_period,
loop_shift,
0,
0);
For the EL3356, would I then?
KL3356StrainGauge* sg = (KL3356StrainGauge*)slave->instance;
printf( "Begin kl3356_ecConfigure...\n");
//
// Create the slave configuration
//
if (!(sg->sc = ecrt_master_slave_config(
master,
slavePosDomain, slavePosIndex, // Bus position
vendorId, productCode
// Slave type
)))
{
printf(
"kl3356_ecConfigure -- Failed to get slave configuration.\n");
return FALSE;
}
//
// Register startup configuration for the hardware
//
ecrt_slave_config_sdo8( sg->sc, 0x1C12, 0, 0 ); /* clear sm pdo 0x1c12 */
ecrt_slave_config_sdo8( sg->sc, 0x1C13, 0, 0 ); /* clear sm pdo 0x1c12 */
ecrt_slave_config_sdo16( sg->sc, 0x1C12, 1, 0x1600 ); /* download pdo 1C12 index */
ecrt_slave_config_sdo8( sg->sc, 0x1C12, 0, 1 ); /* set number of RxPDO */
ecrt_slave_config_sdo16( sg->sc, 0x1C13, 1, 0x1A00 ); /* download pdo 1C13 index */
ecrt_slave_config_sdo16( sg->sc, 0x1C13, 2, 0x1A02 ); /* download pdo 1C13 index */
ecrt_slave_config_sdo8( sg->sc, 0x1C13, 0, 2 ); /* set number of TxPDO */
//
// Configure the hardware's PDOs
//
if (ecrt_slave_config_pdos(sg->sc, EC_END, kl3356_syncs))
{
printf(
"kl3356_ecConfigure -- Failed to configure PDOs.\n");
return FALSE;
}
struct timespec cur_time;
clock_gettime(CLOCK_REALTIME, &cur_time);
size_t loop_period = globalScanRate_us * 1000;
if ( loop_period == 0 ) loop_period = 1;
size_t loop_shift
= loop_period - (cur_time.tv_nsec % loop_period);
ecrt_slave_config_dc(
sg->sc,
0x0300,
loop_period,
loop_shift,
0,
0);
Thanks!
Thomas C. Bitsky Jr. | Lead Developer
ADC | automateddesign.com<http://automateddesign.com/>
P: 630-783-1150 F: 630-783-1159 M: 630-632-6679
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From: Graeme Foot <Graeme.Foot at touchcut.com<mailto:Graeme.Foot at touchcut.com>>
Date: Friday, February 19, 2016 at 7:24 PM
To: Thomas Bitsky <tbj at automateddesign.com<mailto:tbj at automateddesign.com>>, "etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>" <etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>>
Subject: RE: Distributed Clocks
Hi,
I don’t see in your code calls to ecrt_slave_config_dc().
For the yaskawa drive, during the config stage, I use the following calls:
// set interpolation time period (free run mode)
// where 0x60C2 is time in seconds = (0x60C2, 0x01) x 10^(0x60C2, 0x02)
// eg period of 1ms:
// (0x60C2, 0x01) = 1
// (0x60C2, 0x02) = -3
// => 1 x 10^(-3) = 0.001s
ecrt_slave_config_sdo8(dev->slaveConfig, 0x60C2, 0x01, (uint8_t)g_app.scanTimeMS);
ecrt_slave_config_sdo8(dev->slaveConfig, 0x60C2, 0x02, (int8_t)(-3));
// set up the distributed clock
// 0x0000 = free run, 0x0300 = dc
// (Supported DC cycle: 125us to 4ms (every 125us cycle))
ecrt_slave_config_dc(dev->slaveConfig, 0x0300, g_app.scanTimeNS, 500000, 0, 0);
0x60C2 shouldn’t be necessary for dc mode, but I used it before I had dc mode working and have never tried it without and it doesn’t harm anything having it in.
The second value that is being passed to the ecrt_slave_config_dc method is a value that is written to the ESC register 0x980. The Yaskawa SGDV doco says this value should be 0x0000 for free run mode and 0x0300 for dc mode. Other ESC’s may required different values.
I’ve never been able to get the EL7041 stepper modules to work in dc mode.
Graeme.
From: etherlab-users [mailto:etherlab-users-bounces at etherlab.org] On Behalf Of Thomas Bitsky Jr
Sent: Saturday, 20 February 2016 1:09 p.m.
To: etherlab-users at etherlab.org<mailto:etherlab-users at etherlab.org>
Subject: [etherlab-users] Distributed Clocks
Hello.
I’ve been using the EtherCAT master for years to great success, but I’m stuck on a problem I can’t figure out that I think several people here are doing successfully. I can’t implement distributed clocks in my application.
I am having the same problem on two systems I have up and running:
SYSTEM ONE:
EtherLAB Master 1.52, E1000E Driver, Scan Rate 4Khz, Ubuntu Server 14.04LTS, RT-PREEMPT 3.12.50-rt68
alias=0, position=0, device=EK1100
alias=0, position=1, device=EL1104
alias=0, position=2, device=EL2004
alias=0, position=3, device=EL9510
alias=0, position=4, device=EL3356
alias=0, position=5, device=Kollmorgen AKD
alias=0, position=6, device=MTS LVDT
SYSTEM TWO:
EtherLAB Master 1.52, E1000E Driver, Scan Rate 8Khz, Ubuntu Server 14.04LTS, RT-PREEMPT 3.12.50-rt68
alias=0, position=0, device=EK1100
alias=0, position=1, device=EL3001
alias=0, position=2, device=EL1104
alias=0, position=3, device=EL1104
alias=0, position=4, device=EL1104
alias=0, position=5, device=EL2004
alias=0, position=6, device=EL2004
alias=0, position=7, device=EL9505
alias=0, position=8, device=EL7041
alias=0, position=9, device=EL7041
alias=0, position=10, device=EL7041
alias=0, position=11, device=EL7041
alias=0, position=12, device=EL7041
alias=0, position=13, device=EL7041
alias=0, position=14, device=EK1110
alias=1, position=0, device=SIGMA5-05
alias=2, position=0, device=Yaskawa SIGMA5-05
alias=3, position=0, device=Yaskawa SIGMA5-05
Both of the system are fully operational. However, for various reasons, I need to implement distributed clocks on these systems. I’ve never been able to get this to work.
What follows is the code I used for both systems to try this. I read through examples on the mailing list, plus the examples, but I’m not seeing what I’m doing wrong. The result is always the same: all the fieldbus cards go into operation, but the servo drives won’t because of “bad configuration.” Take out the distributed clock code, and they work fine. I’m getting away with it for now, but I do need better clock resolution.
The systems have an LRW domain, then a separate read domain and write domain for the servo drive(s) for a total of three domains (LRW, read, write). The yaskawa drives necessitate this. The scan rate is usually 4Khz, but I have tried it at both 1Khz and 8Khz and gotten the same results. Everything about the implementation is fairly straight-forward. There’s just something fundamental about the DC configuration that I’m not understanding.
Almost all the code below is taken right from the examples or the message boards (thanks, everybody!). If anyone could tell me what I’m going wrong or offer any insights, it’s greatly appreciated. For brevity, I tried to narrow it down to relevant parts, but please let me know any additional information or code I can provide.
Thank you in advance,
Tom
**********************************************************
// EtherCAT distributed clock variables
#define DC_FILTER_CNT 1024
#define SYNC_MASTER_TO_REF 1
static uint64_t dc_start_time_ns = 0LL;
static uint64_t dc_time_ns = 0;
static uint8_t dc_started = 0;
static int32_t dc_diff_ns = 0;
static int32_t prev_dc_diff_ns = 0;
static int64_t dc_diff_total_ns = 0LL;
static int64_t dc_delta_total_ns = 0LL;
static int dc_filter_idx = 0;
static int64_t dc_adjust_ns;
static int64_t system_time_base = 0LL;
static uint64_t wakeup_time = 0LL;
static uint64_t overruns = 0LL;
/** Get the time in ns for the current cpu, adjusted by system_time_base.
*
* \attention Rather than calling rt_get_time_ns() directly, all application
* time calls should use this method instead.
*
* \ret The time in ns.
*/
uint64_t system_time_ns(void)
{
struct timespec ts;
clock_gettime(GLOBAL_CLOCK_TO_USE, &ts);
return TIMESPEC2NS(ts);
}
static
void sync_distributed_clocks(void)
{
uint32_t ref_time = 0;
uint64_t prev_app_time = dc_time_ns;
dc_time_ns = system_time_ns();
// set master time in nano-seconds
ecrt_master_application_time(master_, dc_time_ns);
// get reference clock time to synchronize master cycle
ecrt_master_reference_clock_time(master_, &ref_time);
dc_diff_ns = (uint32_t) prev_app_time - ref_time;
// call to sync slaves to ref slave
ecrt_master_sync_slave_clocks(master_);
}
/** Return the sign of a number
*
* ie -1 for -ve value, 0 for 0, +1 for +ve value
*
* \retval the sign of the value
*/
#define sign(val) \
({ typeof (val) _val = (val); \
((_val > 0) - (_val < 0)); })
/*****************************************************************************/
/** Update the master time based on ref slaves time diff
*
* called after the ethercat frame is sent to avoid time jitter in
* sync_distributed_clocks()
*/
static unsigned int cycle_ns = 1000000; // 1 millisecond
void update_master_clock(void)
{
// calc drift (via un-normalised time diff)
int32_t delta = dc_diff_ns - prev_dc_diff_ns;
prev_dc_diff_ns = dc_diff_ns;
// normalise the time diff
dc_diff_ns =
((dc_diff_ns + (cycle_ns / 2)) % cycle_ns) - (cycle_ns / 2);
// only update if primary master
if (dc_started) {
// add to totals
dc_diff_total_ns += dc_diff_ns;
dc_delta_total_ns += delta;
dc_filter_idx++;
if (dc_filter_idx >= DC_FILTER_CNT) {
// add rounded delta average
dc_adjust_ns +=
((dc_delta_total_ns + (DC_FILTER_CNT / 2)) / DC_FILTER_CNT);
// and add adjustment for general diff (to pull in drift)
dc_adjust_ns += sign(dc_diff_total_ns / DC_FILTER_CNT);
// limit crazy numbers (0.1% of std cycle time)
if (dc_adjust_ns < -1000) {
dc_adjust_ns = -1000;
}
if (dc_adjust_ns > 1000) {
dc_adjust_ns = 1000;
}
// reset
dc_diff_total_ns = 0LL;
dc_delta_total_ns = 0LL;
dc_filter_idx = 0;
}
// add cycles adjustment to time base (including a spot adjustment)
system_time_base += dc_adjust_ns + sign(dc_diff_ns);
}
else {
dc_started = (dc_diff_ns != 0);
if (dc_started)
{
// record the time of this initial cycle
dc_start_time_ns = dc_time_ns;
}
}
}
struct timespec dcTime_;
int
ecatMain_process(void* lp)
{
ecrt_master_receive(master_);
clock_gettime(CLOCK_REALTIME, &dcTime_);
ecrt_master_application_time(master_, TIMESPEC2NS(dcTime_));
ecrt_master_sync_reference_clock(master_);
ecrt_master_sync_slave_clocks(master_);
ecrt_domain_process(lrwDomainMgr_.domain);
ecrt_domain_process(noLrwWriteDomainMgr_.domain);
ecrt_domain_process(noLrwReadDomainMgr_.domain);
… // handle my business
// write application time to master
clock_gettime(CLOCK_REALTIME, &dcTime_);
ecrt_master_application_time(master_, TIMESPEC2NS(dcTime_));
if (sync_ref_counter_)
{
sync_ref_counter_--;
}
else
{
sync_ref_counter_ = 1; // sync every cycle
ecrt_master_sync_reference_clock(master_);
}
// send process data
ecrt_domain_queue(lrwDomainMgr_.domain);
ecrt_domain_queue(noLrwWriteDomainMgr_.domain);
ecrt_domain_queue(noLrwReadDomainMgr_.domain);
// sync distributed clock just before master_send to set
// most accurate master clock time
sync_distributed_clocks();
// send EtherCAT data
ecrt_master_send(master_);
// update the master clock
// Note: called after ecrt_master_send() to reduce time
// jitter in the sync_distributed_clocks() call
update_master_clock();
return 1;
}
int
ecatMain_start(void* lp)
{
//
// domain regs must end in a null entry
//
lrwDomainMgr_.domainRegs = realloc(
lrwDomainMgr_.domainRegs,
sizeof(ec_pdo_entry_reg_t) * (lrwDomainMgr_.size + 1) );
memset(
&(lrwDomainMgr_.domainRegs[lrwDomainMgr_.size]),
0,
sizeof(ec_pdo_entry_reg_t) );
noLrwReadDomainMgr_.domainRegs = realloc(
noLrwReadDomainMgr_.domainRegs,
sizeof(ec_pdo_entry_reg_t) * (noLrwReadDomainMgr_.size + 1) );
memset(
&(noLrwReadDomainMgr_.domainRegs[noLrwReadDomainMgr_.size]),
0,
sizeof(ec_pdo_entry_reg_t) );
noLrwWriteDomainMgr_.domainRegs = realloc(
noLrwWriteDomainMgr_.domainRegs,
sizeof(ec_pdo_entry_reg_t) * (noLrwWriteDomainMgr_.size + 1) );
memset(
&(noLrwWriteDomainMgr_.domainRegs[noLrwWriteDomainMgr_.size]),
0,
sizeof(ec_pdo_entry_reg_t) );
//
// NOTE: the Output Domain must be registered with
// ecrt_domain_reg_pdo_entry_list before the Input Domain otherwise you
// will not have any data exchanged even though the drive goes into OP
// mode.
//
PRINT("\nAttempting to register PDOs on WRITE ONLY domain...\n");
if (ecrt_domain_reg_pdo_entry_list(
noLrwWriteDomainMgr_.domain, noLrwWriteDomainMgr_.domainRegs))
{
PRINT("WRITE ONLY PDO entry registration failed!\n");
return FALSE;
}
PRINT("\nAttempting to register PDOs on READ ONLY domain...\n");
if (ecrt_domain_reg_pdo_entry_list(
noLrwReadDomainMgr_.domain, noLrwReadDomainMgr_.domainRegs))
{
PRINT("READ ONLY PDO entry registration failed!\n");
return FALSE;
}
//
// And now we register the bi-directional domain.
//
PRINT("\nAttempting to register PDOs on LRW domain...\n");
if (ecrt_domain_reg_pdo_entry_list(
lrwDomainMgr_.domain, lrwDomainMgr_.domainRegs))
{
PRINT("LRW PDO entry registration failed!\n");
return FALSE;
}
/*
* Finishes the configuration phase and prepares for cyclic operation.
* This function tells the master that the configuration phase
* is finished and the realtime operation will begin.
* The function allocates internal memory for the domains and calculates
* the logical FMMU addresses for domain members.
* It tells the master state machine that the bus configuration is
* now to be applied
*/
PRINT("\nAttempting to activate ECAT master...\n");
if (ecrt_master_activate(master_))
{
PRINT(
"%s Failed to activate master!\n",
__FUNCTION__ );
return FALSE;
}
/*
* Returns the domain's process data.
*/
PRINT( "%s getting LRW process data from master.\n", __FUNCTION__ );
if (!(lrwDomainMgr_.processData
= ecrt_domain_data(lrwDomainMgr_.domain)))
{
PRINT(
"%s set ecProcessData -- domain data is NULL!\n",
__FUNCTION__ );
return FALSE;
}
if (!(noLrwReadDomainMgr_.processData
= ecrt_domain_data(noLrwReadDomainMgr_.domain)))
{
PRINT(
"%s set read ProcessData -- domain data is NULL!\n",
__FUNCTION__ );
return FALSE;
}
if (!(noLrwWriteDomainMgr_.processData
= ecrt_domain_data(noLrwWriteDomainMgr_.domain)))
{
PRINT(
"%s set write ProcessData -- domain data is NULL!\n",
__FUNCTION__ );
return FALSE;
}
… // blah blah blah
doScan_ = TRUE;
PRINT( "%s completed successfully.\n", __FUNCTION__ );
return TRUE;
}
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